/SQT/

>>7709400
What do you even mean what is the cause of the different wavelengths of light? Wavelength is a property of waves.

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>>7709400
>What are the causes and implications of wavelengths of light?
This right here. This shit.

If photons truly are particles, is this particle as a whole the "electromagnetic wave"? Isn't there no actual difference between electric and magnetic fields? Is the flux observed in this what gives the frequency and wavelength?

Is all this shit just explaining that light is its own deal, and not simply observing the fluctuations in the aether?

Seriously, what the motherfuck is going on? I know how radiation behaves to some extent, but what is it? No longer am I willing to interpolate the answer. I get treated like a fuckhead when I extrpolate. So go on, what the hell do we think it is this time.

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Is this place a meme? Considering to study there for engineering, but nobody in my area knows what it is. Is it worth OOS tuition?

>>7709431
Light is its own deal.

There is no aether or at least if there is its nothing like Newtons luminiferous aether. It would have nothing to do with the propagation of light and it cannot be an absolute standard of rest.

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reposting

Can anyone tell me how my teacher solved this telescoping series?

I don't understand what he did

>>7709400
Civil Eng student here.

In Stiffness method of analysis, how would you draw the final internal FBD for a plane frame with forces directly on its joints?

>>7709465
dem sigmas though
the top bar and bottom bar are horizontal.


your teacher used 1/(n(n+2)) = 1/2n - 1/(2(n+2))

So when you sum this from 1 to k and change variables, you're left with only the first two terms minus the last two terms. If you take the limit, you only have 1/2* (1 and 1/2)

try it and see if you can do it

>>7709431
Light just seems to be one of those things in science that never have good explanations.
Kinda like the cause of the Big Rip scenario and anything in chemistry.

Like, I don't even know now if light is a continuous wave as it's often depicted or if each photon is an independent wave peak travelling through space.

>>7709431
>If photons truly are particles
That's what we call them, but you shouldn't assume too much from that word.

>is this particle as a whole the "electromagnetic wave"?
Electromagnetic waves are waves in the electric and magnetic fields. The values of both the electric field and magnetic field are oscillating, and how far along the field is in the oscillation depends on where you are; that's a wave. That's the classical picture, at least. Quantum mechanics makes things more complicated with the fields not having one specific value unless you measure it and all, but the classical picture is still a useful approximation, and is usually the most relevant when thinking about visible light. Now quantum mechanics says that if you measure the amount of energy in the electromagnetic wave, the answer will be one of several discrete energy levels. The ground state is what we call no photons, and excited states are 1 photon, 2 photons, 3 photons, and so on.

>Isn't there no actual difference between electric and magnetic fields?
The electric and magnetic fields are two different things, but what is a pure electric field in one reference frame will be an electric and magnetic field in another reference frame, and vice versa. They are each three components of one field.

>>7709400
repost

Anyone give me a hint?
Any Set of 5 integers EX. (1, 2, 5,7, 11)

There are 3 integers that have a sum that is divisible by 3. (2, 5 ,11)

Why does this work? I tried figuring out with evens and odds but came to a dead end.

>>7709574
look at it modulo 3. So you have 5 numbers from {0,1,2}. From there, its easy to see that its impossible to pick 5 with no subset that divides 3.

cannot have 3 of a kind (obviously) because 3x mod 3=0
Therefore you must have at least one of each 0,1,2. But then, 0+1+2 mod 3=0

>>7709646
Thanks!
Book I have doesn't have hints. Felt dumb as soon as you said modulo3

>>7709481
>your teacher used 1/(n(n+2)) = 1/2n - 1/(2(n+2))

I'm still not sure what the fuck this is

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sin(x) = 3/5 -- x in the second quadrant
What is tan(pi-x)?

I've solved it to (plusminus) 3/4, but I don't know if the final answer should be positive or negative. I've tried checking using arc functions but it just confuses me.

Can anyone have a look? Thanks in advance.

My Thermodynamics teacher has stated the following:

1) Work done by the environment on a thermodynamical system increases the internal energy of the system;
2) Work done by the system on the environment decreases the energy of the system;
3) The infinitesimal work done by the environment on a system is given by dW = - PdV.

Why is dW negative?

Question.
You have 3 different tables and you have to arrange them side to side so that you can place a symmetry line somewhere. How many combinations are there and how would you calculate it.

The question isn't very well made and doesn't specify anything more than that

Chances of getting into CP Pomona, SDSU, or CSU Long Beach with over 60 credits and all the Math done? I don't have any of the physics courses done, but I'll be taking Physics I during the spring.

>>7710747
Computer Engineering major.

Give me advice for studying for a scholarship test.
I only need help on how to approach studying the math part, if it's not a bother would anyone be so kind as to help me?

Math: Numbers and expressions, Quadratic functions, Figures and measurements, The number of possible outcomes and probability, Properties of integers, Properties of figures, Miscellaneous Expressions, Figures and equations, Exponential and logarithmic functions, Trigonometric functions, The concepts of differentiation and integration, Sequences of numbers, Vectors, Complex plane, Curves on a plane, Limits, Differential and Integral Calculus.

I'm really sorry if this is not the place to ask, but I require help. I really want to get this scholarship so I can leave my fucking third world country.

Anyone know what a nutrient sink is?
I wrote it down during a lecture and circled it but I don't remember what it was.
It was in relation to the microbial conditions of aquatic environments.
Can't find shit when I googled it.

Why cant we research real catgirl genetic engineering?

I really cant imagine any problems, aside from finding a mother willing to give birth to potential failures.

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Anyone have this article?
Koska, J., Spassov, V. Z., Maynard, A. J., Yan, L., Austin, N., Flook, P. K., & Venkatachalam, C. M. (2008). Fully automated molecular mechanics based induced fit protein− ligand docking method. Journal of chemical information and modeling, 48(10), 1965-1973.

Damn thing isn't in my workplace's catalogue.

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what is wrong with my calculator

>>7711103
Close to asymptote. Series diverges near-by.

>>7711103
>>7711109
This is the asymptote btw
http://www.wolframalpha.com/input/?i=tan%283pi%2F2+radians%29

>>7711050
We could ask any women who have slept with you to do it. We already know they're ok with that risk.

A while ago an anon posted a link to an iq test as well as a picture test and said it was for data gathering. I was wondering if anyone had those saved as they seemed to be a lot better then the other stuff online.

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Pic related is bothering me (aside from the arithmetical errors).

It's for that problem where you have a $100 stock and on any given day its value can either increase by 30% or decrease by 25%, you're then asked to find what the value will be after some number of days (usually 100).

What's getting me about the solution however is this.

Why is the expected value of X_n very large? When we later find that the value of X_n tends to 0 as n becomes large?

>>7709400
Someone explain Smolyak sparse grid quadrature to me in a really really dumbed down way please.

Any good resource that teaches me how to analyze a set of data?

>>7712259
(I mean in terms of statistics/machine learning/neural networks)

Is there a particular notation for "an approximation of x" or any other such variable?

>>7712515
~x ?

>>7712546

Seems to be what I want.

How the fuck do you find x?
sqrt(x) = -2x + e^sprt(x)

Some extensive resources for understanding epsilon-delta proofs of limits and continuity?
I haven't found enough examples to generally "get it" and the lecture examples left me with an empty, unsatiated feeling.

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Just finished an introductory course on algebraic structures. We used a few results from number theory throughout, and now I'm wanting to learn more about it. I'm at my uni's library and will be for a few more hours, anyone care to recommend a decent text on introductory number theory?

>>7712955
Rosen is usually where they start for undergrads.

>>7712691
>sqrt(x) = -2x + e^sprt(x)
I don't think you can solve that exactly.

If sine is defined by the ratio of the two sides in a right triangle how is it able to be used in non-right triangles?

>>7712898
Why is there such little material on epsilon-delta proofs? And why am I expected to just pull deltas out of the hat? Am I just retarded and the majority isn't?

>>7713055
Open literally any intro to real analysis and youll see lots of examples

Even Khan academy has a video

Anyone have any resources or a base design I can work with to design a microprocessor in verilog.

Something that could perform addition and subtraction between registers.

>>7709493
http://youtu.be/RwdY7Eqyguo?t=14m40s

>>7713254
There's not enough examples for different types of non-linear functions, not in the course book (Brannan) or the internet.
Can you recommend a book?

>>7713980
If the function is C^1 then you can always take
[math]\delta = \frac{ \varepsilon}{\sup{ |f'| }} [/math]

>>7713993
We aren't allowed to derivate yet.

Anyone here go to San diego city college? I sent my transcripts over there and they told me that my transcripts need to be evaluated before they can clear pre-requisites. They also told me that evaluation takes 4-6 weeks. There's only six spots left for the class I need for transfer. Am I fucked?

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I've been asking this for here for about a week but I never got any answers.

How can I make mercury or another liquid metal attracted to magnets? I'll take any answer you give me

>>7714363
http://www.cchem.berkeley.edu/demolab/demo_txt/paramagnetism.htm

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I don't understand this step, shouldn't there be acos(theta) in the denominator? Also why are the bounds what they are if the region is a circle at the origin with radius r?

>>7714566
whoops meant to say radius a

How do I change scale of grades?

Current scale:
Total points: 30 points
correct: 16

Do I just add 30-16 = 14, so I just subtract from 100?

>>7714798

The new scale should be from 100 points instead of 30.

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Please help me solve, this. I know it's supposed to be easy but can't seem to figure it out. So far I have:
Var(X^2) = E(X^4) - E(X)^4
I can easily compute E(X)^4 = (3/2)^4
But how the hell do I calculate E(X^4)? Should it be E(X)*E(X)*E(X)*E(X)? Please help lads.

Whats the point of learning Reinmann Sums when definite integration is way easier, and actually gets the area?

Are there any good online resources/lessons for learning MatLab?

>>7714798
>>7714807

Nevermind, I figured it out.

>>7714845
mathworks dot com -->support-> tutorials

This is usually good enough. But MatLab is pretty intuitive, after 5 lessons or so, you should be okay and will probably learn the rest by just using it.

>>7714853
Thanks

where can I ask some advice about a civil engineering project? I'm thinking about resuming what I dropped in high school, though there're a few things I wanted to verify.

>>7709400
Now light obviously doesn't have a rest mass, but it also carries energy - which is mass.
If you put a bunch of energetic photons in a box, that box will increase in mass.

Does this then mean that a beam of light travelling through the universe will bend spacetime like if there was a massive object moving there? Would a laser beam from a laser the size of a galaxy make stars and planets fall into it when it moves past them?

I know (R, T) with T the lower limit topology { [a, b) | a, b in R } is not connected as the union of (-∞, t) and [t, ∞) for a random real number is R, but why is (R, T) not path-connected? For all x, y in R f: [0, 1] → R, z → zx + (1-z)y is contained within R, right? But if (R, T) would be path-connected it should follow that it is connected, which is a contradiction.

Why is it that every time I exercise I feel stupid? My memory is bad, I can't think logically. From what I've read online it has something to do with the glucose levels in your body that are being used by muscles and other organs due to the increased physical activity. Some suggested to eat something high in carbs after a workout. I've tried this but it didn't work. Still fog in my head which lasts about an hour or so.

Doing practice questions on algorithm analysis and looking at the solution of a task, I stumbled upon this:
[eqn]\sum_{k=j}^{i+j}(j+i-k)= \sum_{k=1}^{i}k[/eqn]
Why is this true? Am I missing something?

Okay, so explain evolution in the simplest way possible, but not TOO simple.

I slightly got it I think.


>Billions of species on Earth to fill niches
>Every once in a while all niches get filled and animals have to out compete one another
>Species with the best genetic traits live on and on go changes via genetic mutation
>If the genetic mutation is good then these traits get passed on. If they're bad then they usually don't pass on
>Animal sizes dwindle down to the best fit


Do I have it somewhat right?

>>7715635
Can't help you but damn, I'm so excited to take Topology now that I've aced Real Analysis.

>>7715853
>now that I've aced Real Analysis
props man, i know that's a good feel.

what text did your course use?

>>7715644
Your brain almost uses more glucose than every other organ combined

>>7715820
Nope that's right

For the sum on the left,
k=j, (j+i-j)=i
k=j+1, (j+i-(j+1))=i-1
k=j+2, (j+i-(j+2))=i-2

So, each of these iterations, as k increases by one, can be written as an arithmetic sequence.

a_n=i-(n-1), where n=iteration

The sum of every term in this sequence from n=1 to n=i+1 is as follows,

S=(i(i+1)/2)

The sum on the right of the equals sign in your post is simple, and it can be written as

S=(i(i+1)/2)

Which is the same as the previous formula. Yes, both of your summations are the same.

>>7715820
It's true. I was typing out a response but
>>7715887
gave a much clearer write up. Basically the idea is that as k goes from j to i + j, then (j + i - k) goes from the top down (from the largest value to the smallest value) where as when k goes from 1 to i, (k) goes from the bottom up (From the smallest value to the largest value)

thats a pretty neat trick to learn, it can make some summations easier, and might lend some intuition into things like mobius inversion

>>7715884
So in my case, it just takes longer than most people because my glucose levels take longer to restore themselves? I'm guessing there's a genetic component to this?

>>7715820
Let [math]l = k - j[/math]
It's easy to see that the left part of the equation equals to
[math]\sum\limits_{l=0}^{i} (j + i - l - i) = \sum\limits_{l=0}^{i} (i - l)[/math]
Which is just [math]\sum\limits_{l=0}^{i} l = \sum\limits_{l=1}^{i} l [/math]
Change back l to k and you get
[math]\sum\limits_{k=1}^{i} k [/math]

>>7715887
>>7715890
I think I get it now, thanks!

>>7715635
The problem is that your path is not really a path (ie. is not continuous), for example, if x < y, [math]f^{-1}(\{[y,\infty)\}) = \{0\}[/math] which is not an open subset of [0,1].

>>7715918
Samefag, just thought of some improvement of the answer:
Actually, (R,T) is much more than not path-connected, every path is constant.
The thing to notice is that the connected components are point sets. You wrote the argument yourself: if a < b, then writing R = (-oo,b) U [b, oo) ) gives you a partition of R into disjoint open sets, one of which contains a and the other b.
Since the image of a connected set by a continuous map is connected, it follows that the only paths (ie. continuous maps [0,1] -> (R,T) ) are the ones that don't move at all.

>>7715918
Ohh ofcourse; I was so hung up on the path being contained in intervals in R I forgot to think about how f would behave with regard to the topologies.

>>7715948
Youre right, that is an even stronger statement about its connectedness. I thought something was odd.

By the way, I love how you improvised the lemniscate with oo. Gets the job done. Thanks for your answer!

>>7715853
Nice dude. Real analysis gave me a lot of shit when I first took it, its a hard course so acing it is damn impressive. If you liked it youll love topology.

>>7714811
>multiple choice
Literally just fill in the definition
>Var(X^2) = E(X^4) - E(X)^4
I don't think that's correct, unless E(X^2)^2 = E(X)^4

>>7710642

Not quite sure, but I'll take a wild guess. Assuming that you have 3 tables, and a combination = one group or one arrangement of these 3 tables, then this can be represented by 3C1 where 3 represents the total amount of tables and 1 represents one arrangement, thus the combination = 3. I don't know if this is right, I apologize if it isn't as I am still learning the basics. But, that's my word.

>>7716000
you serious nigga?
it's the first caracteristic of variance that everyone sees...

>>7716021
Nigga...

>>7715825
>>7715825
bumping in hopes someone will tell me something.

>>7716000
>>7716021
>>7716075
Original poster, so Var(X^2) = E(X^4) - E(X)^4 is not correct?

I thought variance was defined as Var(X)=E(X^2) -E(X)^2?

Yeah I know it's multiple choice and should be easy, but I still can't figure how to compute E(X^4), shouldn't it just be the integral from 0 to 3 of (t^4)/3 dt?

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does my integral test accurately say that the function is divergent?

thank you, hope you have nice holidays.

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>>7716288
You fucked up the u-sub. Lots of other tests also work with this series, so you shouldn't have to resort to the integral test (though it still works).

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A camera or some shit is sitting on a pole and can only move its view up or down within the 35 degree green area as seen in the side section down below, but it can turn around in a 360

Can someone just confirm this is indeed the area squared that the camera or whatever's able to cover?

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Okay so let me let it be known first I'm not super tech savvy, most of my knowledge is just a loose collection of tech savvy friends who's shown me stuff or told me stuff and trail & error along with a few how to's off youtube.

Alright to the matter at hand I have a 7 year old ASUS laptop things falling a apart and its sort of a house of cards right now, I have a 2013 Toshiba laptop which was given to me for Christmas 2 years ago but I refused to leave my ASUS and have stuck with it all this time.
What I want to do is put the hard drive off my ASUS into the Toshiba laptop, I tried this today but failed, I was able to remove the hard drive and all, even got it in there but when booting it up I got a "media check....[FAILED]" several times and it asking me to reboot I tried this a few times putting the rubber Toshiba harddrive cover over my ASUS hard drive and all but nothing would work, so I just put everything back to what it was and here I am still on my declining ASUS.
What I wish to do its generally have my computer as it is on a new computer, the Toshiba has Windows 8 and I don't want Windows 8 I wish to keep my Windows 7 from my ASUS or at the least have Windows 7, which is partly why i just want to swap hard drives old brain new body, don't have to change a thing but maybe some software updates, but since that didn't work I'm trying to figure out a way to switch everything over to the new-er laptop.

I have a 1TB external hard drive which I have transferred basically things of importance but I know I'll miss some things, I'm extremely disorganized, another reason I would have just loved to swap hard drives but yeah, whats your reading of the situation? any solutions? best case would be to have a clone of my computer on the new one, but I'm starting to doubt thats going to happen.

>mfw computer stuff

(was told to try asking here by /g/)

>>7716870
Did you connect all the cables? The assholes on /g/ are fucking with you by sending you here but without knowing more I cant help you. Theyre both 2.5" SATA drives, right? Have you tried going into the boot menu to select your new drive as the bootable medium? Checked the BIOS settings? I wont be around today, try to Google these things for a bit.

What are the applications of topology?

Whenever someone makes the next "groundbreaking discovery" by finding the formula to turn a 4 dimensional donut inside out, I think "what has mankind gained from this?

Is topology really a meme field?

>>7716682
pls respond

>>7717485
Generally in these cases it's that some other magician in another field can use that information to model a previously problematic astrophysical phenomenon, and the information gained from that eventually yields something applicable to our own solar system, which is in turn utilized by NASA engineers to make alterations to their rocket technology which make Mars landings slightly more viable.

Basically the corpus of modern science has been unapproachable on an individual level for a while now, and most discoveries that have an immediately perceivable utility to mankind are made through a hive mind like model.

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[math]lim_{x\rightarrow \infty} (x+1>x)[/math]
Is it true, undefined, or not true?

>>7717572
Don't tell me what to do.

>>7717679
It's false.

>>7717586
>>7717485
https://en.wikipedia.org/wiki/Network_topology

>>7717679
lim (x → ∞) [x+1] == lim (x → ∞) [x] but what you posted has no meaning, its abuse of notation.

>>7717572
So there are two axis? If so, 35 up and down makes for [-35, 35] and 360 around makes for [0, 360], this is a section of the sphere looking a bit like a fucked up donut. I have no idea how your image relates to this.

>>7716682

Area of circle =pi r^2, r is the radius

pi*281^2 - pi*50^2 = 240209.3 m^2

>>7710509
dW is not necessarily negative, the negative sign only states that it is the opposite sign of dV, since P must be positive. If dV is negative (volume is decreasing) then dW is positive (system is doing work), if dV is positive (volume is increasing) then dW is negative (system is receiving work)

>>7717860
I did this exact calculation and got that answer of 190000, but thanks

>>7717698
I was just basically trying to visualise it a bit better

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Hey mathfags. Reading up on some topology (which I'm taking next quarter) and I had a question about handles. So in the shitty drawing I attached, the first sphere has one handle, the second has two. But what would the third have? It's a handle with another handle attached to to it. Does this count as a separate structure or is it equivalent to a structure with two handles?

>>7718682
I'm like 90% sure its the same as two handles but I may be forgetting some pathological case

>>7718692
Thanks anon.

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How can I check if my solution for trigononometric integration is correct?

I've come up with what I think is an answer, but I don't know if it's correct.

>>7718682
You can slide the handle-handle intersection off the handle getting the 2-handle version

>>7718758
What is differentiation

>>7718758
The answer is B. 16 + 9 = 25

>>7719075
Wait....but 36 = 25 +9.
This game is fraudulent.

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>>7719080

>>7718758

16.

4^2 = 16
2^2 = 4.

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Can someone say if this is correct or not? I feel like Tipler is using the wrong normalization constant for the two identical boson system, because a problem in Griffiths said the result is 1/2.

Guys fast pls I need this funny meme pic where it says like "I want to become a doctor" and then like >lol engeneering masterrace >140k ..

So noise-cancelling headphones work by taking the sound outside the headphone as an input, inverting it, and adding it to what's being played through the headphones, so if the outside noise for a given timeslice is some arbitrary value +5, the inverse is -5 and adding those results in 0, so the noise is cancelled.

Is it possible to do this inversion with electromagnetic radiation? e.g. some kind of anti-radar or anti-light

>>7709400
Can someone explain to me why quantum entanglement cant be used to transmit information faster than the speed of light.
If I have 2 quantum entangled particles. And I switch the spin of one particle. The other particle is effected immediately. Can a receiver then not just measure the spin and get information flt about the particle.

>>7719355
AFAIK you can't measure an entangled particle without affecting it

So you can use it to communicate but you can never know when a communication has arrived without observing and, if the entanglement wasn't already used, collapsing it.

Of course, I'm not qualified to talk about this, it's just my layman's understanding of the subject.

>>7719363
>you can't measure an entangled particle without affecting it
You can affect it all you want as long as its still quantum entangled and you didnt change the spin while measuring it.

>>7714566
Looks like a trig substitution. What's the problem exactly?

>>7719355
so you've got an entangled particle, you know someone else has the particle entangled to it.
You perform a measurement. Congratulations.
What does the outcome mean? You keep measuring states and you're sure that your partner is getting the same results since nobody's listening in.
Now what? How does this transform into information?
The bulk of the issues with information transfer is that you need somehow a way--either dynamic or static--to make sense of what the measurements mean and how to verify that your particles are still entangled with the other guy's particles. This making sense business requires getting into contact with someone else or sending new particles or something or other. All these methods are restricted by the speed of light.
Essentially, if you could transmit information instantaneously, then quantum entanglement could be used to transmit information instantaneously. =]

>>7715825
This is pretty hard to decipher senpai.

I remember in elementary school the critical step for me to understand evolution was grasping the fact that individuals do not evolve. Good genes are passed on only by surviving while inferior organisms die (technically, fail to reproduce).

Do you get that? I'm not sure what to say to you. Once I got that the rest became pretty clear, conceptually. You might consider one of those free kiddie textbooks if you're still stuck. No offense but this is pretty elementary, and you'll have to choose your sources accordingly.

In quantum physics

what determines the width of a transition?
is the probability amplitude from state g to e [math] \lvert \bra{e}A\ket{g}\rvert^{2} [/math] the same for the decay process e to g?

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Have to find total work done on this block moving up a ramp. Basically this is what I have so far:

>Fcosx-μmgcosθ-mgsinθ=ma

The block is in contact with the ramp the whole time so should I bother with the Fsinx and the mgcosθ on the block? Not too sure about that one

>Can solve for "a" in previous eq'n so then I can now use W=Fd to find total work done.

Am I right, /sci/?

I just thought of something:

So I'm finishing up my B.S. and I'm applying to a doctorate program at my school; however, I attend a branch campus and not the main campus (which is two hours away.) With the application deadline in two days, should I really worry about transcripts being sent from my school... to my school? Honestly, I don't even see the point in having that done as all my information is in the database. I'll probably have them submitted just in case but then again, are transcripts arriving on time a huge concern for grad school applications, especially if the school already has your documents?

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what would you call this distribution?
(keep in mind that the scale is logarithmic)

>>7720019
im no statistician, but is it not just binomial distribution ish?

>>7720019
Normal, with slight positive skew

>>7720041
do u call it normal even if it's discrete?

Is there a name for the process of converting categorical data to numerical data?

>>7720041
That's a negative skew you fag

>>7720045
Even continuous measurements have a maximum precision.
If you measure to the nearest mm, then all values between 0.5mm and 1.4999mm would be recorded as 1.
Every "continuous" data measurement is technically discrete, it's just that the groups are tiny and often only have 1 (or no) recording in them.

>>7720083
Calm your tits.

It's a log scale, and the mode values fall below the mean.
Even though it looks like most of the values fall in the right half of the distribution, that little peak just below the mean is actually quite a large chunk of the players.

It's probably not very skewed either way on linear graphing.

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Anyone here good with Stats? I am having an issue with conditional probability

>>7720121
probability trees?

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>>7720128
Here is what the question is asking. I already have the answer to 2a here: http://i.imgur.com/9NmUgD8.png

For 2b, don't i just take 95/(95+15) to get that answer or do I need to work in the 13% somehow?

>>7720136
P(drugs)=P(drugs|positive)P(positive)+P(drugs|negative)P(negative)

rearrange to find P(drugs|positive)

>>7720147
Appreciated anon

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>>7720147
So you meant like this anon to find P(drugs) or am I just dumb and you meant something like

p(drugs|Positive)=P(positive)+P(drugs|negative)P(negative)/p(drugs) where drugs = 13%?

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>>7719080
25+9=36.

>mfw

What is the difference between CS and Software Engineering and which one is more about programming?

Is it possible for a moon to be in constant sonar eclipse? Like a gas giant's moon, always in shadow?

>>7720263
SE is about programming CS is (or should be) about algorithms, artificial intelligence, research, theory of computation, etc

>>7720268
In programming or SE, how much CS such as algorithms would be beneficial to know?

>>7709400

Why can surface waves on a lake have different wavelengths and amplitudes? Both the properties of the source (eg. A bobber oscillating the water at a given amplitude) and the properties of the water come into play.

Light is similar. The source could be an atom which resonates at its natural frequency and the water is space. Photons are just waves in the ether. We can deny it all we want but the ether exists and its the only way to account for photons. Tesla and the greatest minds believed in the ether. It's where all mass comes from and where all mass will return.

>>7720280
depends on what you want to do. a lot of interviews at big companies (google, facebook, microsoft) are focussed on algorithm questions that can get quite advanced, and smaller companies sometimes copy them. in your daily work as a SE it depends again on your expectations. a good programmer should have a solid grasp on data structures and algorithms tho, but most programmers are shit so it's not a hard requirement i guess

>>7719149
Yes but 4+4 isn't 16, is it? You just squared 4 again, which isn't part of the problem. The correct answer is B because the square root of 25 also happens to be the sum of 16 and 9, both of which are smaller square numbers than 25.

>>7720294
>>7720268
speaking of SE, I've seen people argue that SE isn't real engineering. Is that true?

>>7720316
idk i dont care about meme debates sorry

>>7720320
meme debates?

>>7720333
whether x is "real" engineering/science/etc. typical /sci/ topics

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I am mapping a big rock in space and PS refuses to work after 10 000 x 10 000 and it is not nearly enough detail. Should I bite the bullet and split the map into sub-parts or is there an alternative way that I have missed?

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Did I fuck up the way I answered this question?
http://i.imgur.com/bSeBNzf.png

I calculated the Observed, the Expected and the Contingency table, along with running a Chi Square Test. I just answered that
"Based on the results from the table, there is a 33.3% chance a non all-star will test positive for doping over an All-Star Player. "

is there an easy way to generate a set of points where the distance between each point is decreasing logarithmically?

that is, a faster sampling rate earlier in the experiment than later

so far what i've come up with is writing an expression for exponential decay and sampling that at successive points to determine the distance between successive points but that feels so hacky

>>7720860
why not a fisher's exact test, given how few data you have?

>>7720866
Professor never touched on Fisher's Exact. I think she just wanted Chi Square for this. I feel like I am going overkill on a problem she said was "easy"

Whats the deal with the multiverse stuff, i mean if every possible eventuality is there why is there not a universe where i am god emperor and build a intentional portal to go and grab every version of me and put inside some kind of matrix where i can live happy

>>7720877
every reality possible to arrive at, not every reality possible to conceive of

to shamelessly steal from neal stephenson: we can conceive of a universe where one microsecond from now, a mile-wide block of ice appears in the middle of the sun. that doesn't mean that will ever or can ever happen

you can glance sideways at the set of universes where you're a god emporer, but that doesn't mean they're ever reachable

>>7720872
oh, then i think you're fine.

Do ALL numbers except squares have an even number of factors? Do all squares have an odd number of factors? For example 56 has 8 factors, whilst 64 only has 7.

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>>7720884
t-thanks

Does teleportation kill you? Lets say we have a machine that can disassemble a human body in room A and transport those (not other) pieces into room B where all piece would be reassembled into the original human with all original parts. (Lets say that all pieces during the transportation do not interact with anything, so they actually stay in their original form).

Until recently I was certain this would mean that the person in room A would die (disassemble brain -> death) and the reassembled person in room B is effectively a "copy" of person A, just that this person is made of the same pieces but still a different person (Person A died after all, so this has to be a new person).

Now I tend to believe this death and resurrection process is not the ultimate death of person A. When in fact our body/brain can hold our consciousness while replacing atoms in our body as we age, obviously making consciousness independent of the materials its made of, but rather dependent on the continuation of its living state.

Now my problem lies whenever person B is just a copy (person A dies, person B gets created) or that person B is in fact the resurrected form of person A, making the death of person A only temporary for the duration of the transport.

>>7720901
>obviously making consciousness independent of the materials its made of
have you considered the idea of: the individual states of consciousness we experience day to day, even minute to minute, are only believed to be identical because we remember a continuous flow of memories connecting the two times

they are not, in fact, the same consciousness - but to the body experiencing it, they might as well be

>>7709400
>anime

die

>>7720906
Interesting, but wouldn't that imply that I die every time my consciousness changes its state?

>>7720915
it implies that consciousness is an artifact of a perceived continuity of experience

you infer, "because i can remember what happened to my body five minutes ago, i have the same consciousness i had five minutes ago"

which isn't necessarily the case

>>7720932
You were claiming that the consciousness changes from moment to moment, and only the memory persists.

Doesn't this mean that the X-1th iteration of consciousness gets replaced by the Xth, effectively erasing consciousness X-1?

>>7720941
it might disappear, it might never have existed in the first place

>>7720945
But we remember it and our perception of "you" persists, as you said.

Now this should mean that an interruption in this chain of memory flow should be the end of an individual (death). This makes teleportation a kill-and-copy machine.

>>7720951
Yes, that's the point I was driving at.

From a hypothetical observer who can view our consciousness as an actual object, it's kill-and-copy. We don't perceive it as kill-and-copy because that's just how we experience the world.

>>7720959
Okay, thanks for clearing this up for me.

Third year mech E. with a shit gpa coming though. How do you figure out what you want to do with this degree?

>>7720971
step back and consider this question: do you actually enjoy the material you're learning? if you could just suddenly transport yourself to a situation where you're being paid a livable wage to do what you're learning every day, would you like it?

your goal in college is to find the subject that fits that criteria

>>7721005
Yeah I've only taken a couple major related upper-divs, and I think they're all really interesting. For me, it's hard pinning it down to an industry.

>>7721016
one easy eay to try to pin it down is to read papers from that sub-field late at night

you're looking for the ones that you can read when you're tired rather than falling asleep because they're boring

You know how a prism diffracts the light in the visible region?
Is it possible to do something similar (probably not using a prism, but anyway...) with wavelengths that belong to the radio frequency area?

>>7721036
Ah. Thanks for the advice!

>>7719764
be safe

Anyone have the pic with the data on how many social scientists could correctly interpret p-values (or something similar to this)

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How do I use math tags? Looked at the guide and still can't figure it out.

[math]\frac{a}{b}[/math]

>>7721491
[math]test^test[/math]

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>>7721496
woops, just doesn't look like it works in thread..

>>7721501
or until I refresh.

So I have to my Analysis I final on Thursday, and I'll have to prove 8 essential theorems of Analysis. Anybody know of a place where I can find straightforward and preferably concise proofs? Do you guys recommend any easy Theorems to pick?

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yeah i have no idea how to do the laplace inverse of this (other than using convolution).

can someone help out?

>>7721506
Proofwiki.org

>>7721176
Y-you too.

>>7721687
Thanks

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Could anyone give me a tip on how to solve this? a is a real number greater than 0.

>>7721651
convultion or use the residue theorem.
convultion is easier on this one. also its easier to understand, if youre not into complex analysis

>>7721976
http://www.wolframalpha.com/input/?i=lim+x^a%2Fe^sqrt%28x%29+as+x+-%3E+infinity
This is infinity/infinity, use L'Hôpital's rule a times and u'll get a!/infinity, which is zero.

Does Medicine fuckin have to largely do with chemistry? I'm don't work that well with chemistry i like physics better, should i take up Medicine, or would i like suffer?

>>7722000
We haven't done L'Hôpital's rule and derivatives yet. So there must be some other way to prove that the value is 0?

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>>7721976
What about this?
Last passage should work because exponential is a higher order infinity than x^a.

>>7722066
than again I have inf/inf, how do I get to 0 without using derivatives?

>>7722084
That's because the exponential function is a higher order of infinity than the power function. It approaches infinity faster and therefore it "dominates".

It's a horrible explanation but it's the only explanation I know.

>>7722084
The last identity that >>7722066 used is just what he meant by "higher order infinity", the exponantial function grows faster than any fixed power of x. If you cant use that fact you can quickly derive it by using the power series representation of exp(x).

Is this

[math]u_1 = A_1 \cdot e^{i(wt - Kx)}[/math]

the same as this?

[math]y = A \cdot sen(wt - Kx + φ_0)[/math]

If not, can anyone pinpoint the differences between them and how can I convert one to another?

Can anyone give me a quick refresher on how to do these? It's not for homework, I already know the answers (17) 1/4 ---- 18) 6 ----- 19) 6 ------ 20) -1) but I'm just curious how to do them cause I forgot

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>>7722511
and I forgot pic

>>7722375

one is complex and one is real. take the real (or imaginary part) and with suitable choice of (complex) A1 you can get from one to the other.

>>7722511
L’Hospital.

>>7722515
Use Le Le Hops
Ex: #17 the bottom when derived becomes 1
and the top becomes

[math]limx \to 1=\frac{1}{2}\frac{1}{\sqrt{x+3}}=\frac{1}{2}\frac{1}{\sqrt{4}} = \frac{1}{4}[/math]

which is as stated above.

>>7722603
someone fix the formatting I'm drunk

>>7722572
>hospital

>>7722618
>Guillaume de l'Hôpital (also written l'Hospital)[...]
https://en.wikipedia.org/wiki/L%27Hôpital%27s_rule#History
If you want to be a prick, at least be right.

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Chances of getting into a cc waitlist class? Rank 5 on chemistry and Rank 3 on Physics. Though, I did sign up at a different community college for Physics, so I'm not that worried about the waitlist for this CC since the professor supposedly sucks at ratemyprofessor with 60+ reviews and a 2.2 rating.

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I'm 23 and want to get into math. Reach the "mathematical maturity" I've heard about. I made it up through calc 1 in college before I stopped. I also took a logic class that covered natural deduction/proofs with pic related, which I fucking loved.

Since I liked proofs in logic so much, I figured I'd like them in math and started with Spivak. I've been struggling a lot with the problems though. It seems like every other problem's answer is like "oh yeah, here's a general assumption we can make in math that isn't related to the basic properties I listed". I learned that proofs are like: number line, make new assertion, list reason.

What do I do? Is there a better book I should start with? I'd eventually like to do the whole rudin undergrad course that's floating around in a /sci/ screenshot somewhere, but at the rate I'm going I feel like I'll be 30 before I get there.

>>7722985

Landau, Differential and Integral Calculus

if you want to know about constructions of the integers, reals, and complex numbers look at Landau, Foundations of Analysis

You could also look at a more advanced logic book like Mathematical Logic by Enderton or Mathematical Logic by Ebbinghaus, Flum, and thomas

Or you could study some Abstract Algebra or number theory. Hardy and Wright is a good number theory text, as is Niven and Zuckerman.

I think this question might be too hard. Is there any handwritten form of the minuscule letter of "Nu" that: 1. Definitely doesn't look like a v. 2. Doesn't look fugly. 3. Doesn't feel awkward writting?

>>7722511
>>7722515
I actively avoid L'Hospital because it obscures a lot of details, and it's often overly complicated.
A much better way imo this:
The root is the obvious problem and you don't want to deal with roots so here's what you do. If you have [math](a-b)(a+b)=a^2+ab-ba-b^2=a^2-b^2[\math]. We want to square that root. If we have [math]\frac{\sqrt{x+c}-b}{x+d}[\math], we want to multiply by the correspodent of (a+b) in the earlier example. Since we'd be changing the value if we just multiplied by it we have to divide by it as well, ie multiply by 1. [math]\frac{\sqrt{x+c}-b}{x+d} \frac{\sqrt{x+c}+b}{\sqrt{x+c}+b} =\frac{|x+c|-b^2}{x+d} \frac{1}{\sqrt{x+c}+b} [\math] and this one is easy to take care of.

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hey /sci/
how does scaling and curving work?

suppose we had the mark breakdown in the pic.

after grading/scaling, what marks would be changed to what? would the marks be shifted right so that the 70-80% is now 90-100%, and likewise, the 20-30% is shifted to the right so that its now 40-50%? or do the bottom marks stay the same but the rest of the marks are sort of "stretched" to fill in the gap between 70-80% and 100?

I want to solve P vs NP just sitting down in my house, studying from internet. I want to check what bibliography says, where should I check? I mean, where should I look for papers and stuff like this that maybe I will need?

>>7709574
(5+7+13)=5^2
(5+7+11)=23
(7+11+17)=7×5?

Any math undergrads here? How good do you have to be at math to be a math undergrad?

I understand math, but I make dumb mistakes. If I get to the course levels where the numbers start mattering less will this become less of an issue.

>>7709400
When I have sex with a girl tonnes of times they get a painful UTI that needs antibiotics. Happened probably ten times with four different girls.

Is this just a reality of having bulk unprotected sex? Or is my dick gross?

>>7723737
it entirely depends on what distribution you want to scale to

if you think that the score increases between the lowest and highest grades were trivial to achieve, then scaling would be appropriate

if you think you don't need to scale, that the overall distribution represents a fair spread around the expected performance on the test, then you just set some new point to be your average grade and look at where the binning falls

>>7724315
it means your dick is disgusting

wash your dick you animal

>>7723737
>Thinks that the class average should be above 60%
Found the americlap

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Is GE really the most useless thing in college?
>8 week short term communication class
>only meet once a week
>professor didn't give us class for two of those 8 weeks
>basically did busy week that amounted to an hour a week
>get an A
>learned nothing

>>7719531
jesus christ just do it with enegry

Just curious and I lack the understanding to answer this myself.

Do objects that have the same mass, also have the same weight?

>>7726105
if they're in the same gravitational field, yes

>>7726105
Only in the same gravitational field. Usually we mean "weight" to mean "force of gravity by an object in the proximity of a much larger object".

So we "weigh" an amount on earth, and a different amount on mars, but the mass is the same. And this "weight" is the same gravitational force that every pair of two particles in the universe experiences

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Help me with this please.
I already have:
[math]\frac{-r\hat\phi}{\sqrt{a^{2}+r^{2}}}[/math]

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Ok so, I think I understand what's going on with a bifurcation diagram when there's one and two lines - at one line, there's just one possible value for the system, and at two, the system bounces back and forth between the two lines endlessly.

But what about further cases, say the region when there's four lines? Does the value of the system jump around between four values in a random progression? Does the system have two separate sets of solutions that are each bouncing around between their individual two limits?

>>7710289
It's called the method of undetermined coefficients. You can rewrite the fraction 1/n(n+2) as A/n + B/(n+2) where A and B are constants. If we multiply all three by the denominator n(n+2) we end up with 1=A(n+2) +Bn. We can then rewrite this as 1=(A+B)n + 2A. The left hand side has no n's, so A+B must be 0, and there for 2A must be 1. Solving this system gives A=1/2 and B=-1/2. If we plug into the original template we get what the other anon said. Then we can see that 1/2n and 1/2(n+2) have the same terms except for the first 2 of 1/2n. This means the two will completely cancel out except for 1/2 and 1/4. These add to 3/4

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How would I solve this?

Sorry, fairly new to calculus, could someone walk me through the steps?

How does the choice of sets when defining a function actually change the object? For example, let [math] A = \{1 ,2\}[/math] and [math] B = \{1 ,2, 3\}[/math]. Then define [math]f: A \to B[/math] by [math]f(1) = 1[/math] and [math]f(2) = 2[/math].

Now I define [math]g: A \to A[/math] for all [math]a \in A[/math] by [math]g(a) = a[/math]. In both cases, the functions represent the following set of ordered pairs:

[eqn]f = \{(1,1), (2,2) \} = g.[/eqn]

But [math]f[/math] and [math]g[/math] are different objects, as [math]f[/math] is not surjective but [math]g[/math] is. How is this possible?

>>7728021
Do you even into type theory?

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>apply to CSU Long Beach, SDSU, CP Pomona
>finish DE this semester with an A at a CC
>check out assist
>realize that LB and SDSU don't even need Calculus III or Differential Equations to transfer
>I want to major in computer engineering
>mfw

Should I even bother going to those schools if they don't even require those classes?

>>7728048
No I don't friend, would you willing to give me the tl;dr? Just looking at this briefly, it looks like an entirely different foundation than ZFC, so would type theory account for this sort of problem but not ZFC?

so im helping my uncle with his calc 1 stuff today and im trying to figure a problem that his teacher gave him. it says, given f'(x) = 0.2t + e^-6t, compute f(6)-f(2) by symbols. what im trying to figure out is, wtf is solving by symbols mean?

>>7728102
Leave the answer exact, in terms of e, rather than computing an approximate value.

>>7728056

mfw i know a computer engy at CP Ponoma who I just helped pass his calc 1 final. mfw hes gonna be a junior next year.

>>7728021
in ordinary set theory, I think you could argue they're the same function exactly because of the argument you presented.

I suppose that if we wanted to further formalize the notion that these functions are different, we could change how we define functions. An example would be defining f as {(1,1,B), (2,2,B)} but that's a bit ugly.

>>7728152
That made me think we could define the function to be an ordered triple, and I found something on stack exchange which seems to back up that this is done (http://math.stackexchange.com/a/60369), so thanks!

>>7709431
what I don't understand is why I can't like have any mass? I mean doesn't everything in the universe that exist have to have some kind of weight? How can something exist if it doesn't Have mass?

>>7727311
>at two, the system bounces back and forth between the two lines endlessly.
No, the lines represent the values the sequence can take asymptotically. That is, the possible equilibria.
This doesn't mean that the sequence only takes two values or that it necessarily oscillates between the two. It just means that these are the only possible limit points of the sequence.

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does an two liquids reaching an equilibrium cost energy?

so if 2 equal size containers of water, one at 40 degrees and at 60 degrees, are combined into a larger container, will the resulting temperature be exactly 50 degrees? or will it be less than that since some energy is used to reach an equilibrium

Not a question, just putting this out there.

>be me
>taking calc 2
>understanding some concepts, struggling with a lot
>post in /sqt/ whenever i have a problem
>you friendly anons answer me and clarify the problem that im having
>end up passing calc 2

thank you all. i really appreciate your honest patience and everything. please have a nice holiday season.

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I know what intermediate value theorem is but how does this help me find a solution for the function? I know it can help me say that there is a solution, but how do I find it?

>>7709400
According to general relativity, time should be at a complete standstill for a photon traveling through a vacuum, and should exhibit no change as it crosses gaps between its emission and absorption, even at intergalactic distances. So what I'd like to know is if anyone has ever looked for evidence to the contrary in deep field astronomy, some kind of statistical discrepancy that indicates slight decay of photons that were emitted billions of light-years away.

Taking Analysis in Several dimensions (using Munkres Analaysis on manifolds) and Differential Geometry next semester. Which one should I get a head start on?

>>7728961
If f(a) > 0 and f(b) < 0 with a<b then you know there is a solution in [a,b].
Now check f(c) with c=(a+b)/2.
If f(c) > 0 then you have a solution in [c,b].
If f(c) < 0 then you have a solution in [a,c],

This way you can always half the size of the interval until, after 10 iterations, it's smaller than 10^(-3).

>>7720019

Im betting a 3-parameter weibull distribution would fit well

>>7728995
Thanks anon, now I understand the steps to approximate. I'm still a bit confused about approximating "the zero to three decimal places" though. What exactly is "the zero"? Is it x where f(x) = 0? Do I just stop when I get a f(x) result with 3 decimal places? I probably get this wrong

>>7728750
Well the hotter water will lose heat and the colder water will gain heat, if the system is adiabatic we can assume all the heat the hotter water loses the colder water gains

q_gain= q_lose
m * Δt * Cp = m * Δt * Cp
T2-40 = 60-T2
T2 = 50

How would you solve

lim (x-> -4) of (x^2 + 2x- 24)/(x+4) ?

Like, if it was (x^2 - 2x - 24) I could've rewritten it as (x+4)(x-6) and then simplify the (x+4).. but not sure how to solve it like this?

>>7728750

Assuming there is no heat transfer to the environment

and that the masses are equal (not volume because volume changes with temperature)

This will result in a mixture of 50 degrees

>>7729003
A zero of a function is any x for which f(x) = 0.
You stop when you're within a distance of 3 decimal places from zero, as in |f(x) - 0| < 0.001 (look up the formal definitions of limits if this is nonintuitive)

>>7729008
A change of variables u = x + 4 might make it clearer.

You could also use L'Hôpital's but that's an overkill

>>7729011
>A change of variables u = x + 4 might make it clearer.
Sorry but I still don't see it? I don't have a x + 4 in the numerator (nor a -x - 4)

>You could also use L'Hôpital's but that's an overkill
Don't i need to have a 0/0 or inf/inf to use L'Hopital?

>>7729015
Doesn't matter, it's so you can get your variable to approach zero and that's easier to work with.
u = x + 4
x = u - 4
lim x-> -4 f(x) = lim u->0 f(u - 4)
work it out to the end and you'll see it.

>Don't i need to have a 0/0 or inf/inf to use L'Hopital?
yeah my bad, I misread the post. the previous part still works though. if you don't get it i can show you the answer.

What is the difference between Schrodinger eq. for real and imaginary time?

>>7729020
>>work it out to the end and you'll see it.
I'm too dumb to figure it out desu, I don't even know what I'm looking for... I get something like (u^2 - 6u -16)/u

Is this on the right track? Do I split it in u^2/u - 6 - 16/u or something? I'd get u - 6 - undefined = 6 ? Sounds like I'm doing something wrong

>>7729026
This is exactly right, you get lim (u->0) of [u - 6 - 16/u] which obviously diverges.

(further explanation: adding a diverging function + a converging function results in a diverging function. u - 6 converges to minus six and 16/u diverges)

>>7729029
oh... that's weird, I didn't expect to get something. does this mean that the function is continuous cause it has no discontinuity? sorry if it's a stupid question

>>7729029
>>7729020
>>7729011

Really? This is the most useless change of variables ever.

To the guy asking the question:

CHECK TO SEE WHAT THE NUM AND DENOM BOTH APPROACH IN THE LIMIT. IF THE DENOM IS ZERO BUT THE NUM IS NOT, THEN THE LIMIT IS DIVERGENT OR DOES NOT EXIST.

>>7729035
That's the shitty highschool way of memorization over understanding
fuck off back to precalc
>>7729034
the limit has to exist and equal f(-4) in order for the function to be continuous at x = -4. since the limit doesn't exist, the function isn't continuous there.

>>7729035
oh really? Are there no exceptions to this? That's pretty cool

>>7729037
>the limit has to exist and equal f(-4) in order for the function to be continuous at x = -4. since the limit doesn't exist, the function isn't continuous there.
Oh okay you're right makes sense thanks anon!!

>>7729021
Plz hlep

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Can this be solved without L'Hopital? I was thinking about multiplying with the conjugate of the numerator, but I don't think I know how to multiply square roots that have multiple terms

>>7729037

Um, no. I have a masters degree in mathematics (what are your qualifications?) and this is how I think about it. It's not even memorization, just common sense. A finite number divided by something approaching zero is infinite. The way you're doing it is pointless.

>>7729042

The exception is infinity/zero.

Here are some useful things:

In the limit, we have

Finite/zero = DNE or +/- infinity depending on circumstances.

Finite/finite = itself

Infinity/finite = +/- infinity

Finite/infinite = zero

Infinite / zero = DNE or +-infinity

Infinity / infinite and zero/zero and and zero / infinite = try another method (substitution or l'hôpital or something)

>>7729042
Let's say we have f(x)/g(x) so lim x->a of f(x) converges to a non-zero number. If lim x->0 of g(x) = 0, 1/g(x) approaches infinity or minus infinity. We get a function f(x) that converges to some non-zero number times a function 1/g(x) that diverges, so their product has to diverge as well.

>>7729056
Working towards my masters but have been TAing for a while now. In order for this stuff to be common sense it has to be understood, otherwise it's just memorization.

>>7729053
There is a famous limit that goes something like this

lim as x->0 of ((1+x)^(1/k) - 1)/(x) = 1/k

Try to manipulate the expression into that and you might solve.

>>7729053
>>7729101
u just multiply by conjugate and u get x-4 in the numerator and solve it from there

Are massive or hollow pipes better for compression? And how about tension?

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Can someone please explain me if this limit is continuous? It's not, right? Cause the denominator is 0 when x = 2 so f(2) is not equal to lim (x -> 2) of f(x).. so it's an asymptotic discontinuity located at 2?

Pls respond

>check my 19 year old niece grade for remedial english
>community college
>36%
>final grade: F

How is this fucking possible, /sci/? mfw she didn't turn anything in. I was wondering why she even kept going to the class. Should I even say anything?

>>7729309

It's continuous when you do the algebra and cancel the equation that makes it discontinuous. The steps is right in the picture.

>>7729309
f(x)=(x^2-4)/(x-2) is not defined at x=2 a priori but f(x) can be extended to be defined at x=2 by doing the algebra and choosing the value f(2)=4

If I'm trying to transfer and get a D in one of my courses in progress, and plan to retake it next semester will my application be thrown out regardless

>>7729456
>19 year old niece
>Should I even say anything?
no.
that's none of your business.

>>7729456

You can give her advice, but that's about it. Don't bring it up unless she does.

>>7729482
>>7729689
But what does this mean? shouldn't a function be continous/discontinuous inherently independent of what algebra I do on it? when i simplify, don't i have to mention "when x =/= 2" to keep them the same? I think what im looking for is "removable discontinuity" but im not too clear on the concept... surely the function shouldn't have its continuity decided on whether I can spot the algebra operations to simplify it?

>>7730466
Well, technically f(x)=(x^2-4)/(x-2) is not even defined at x=2 (in Calculus class anyway). There is an "implicit domain" that is the set of all real numbers except 2. So it really makes no sense to even ask if it is continuous at x=2. If we define a function g(x) to be equal to f(x) at all points except x=2, and further define g(2)=4, then g is continuous. Yes, this sort of thing is referred to as a "removable singularity."

In the context of Complex Analysis, it might be slightly different, as f might be defined to be infinity at x=2. But typically not in Intro Calculus.

>>7730472
Okay that clears things up a bit thanks, I should look into complex analysis sounds cool

>>7730472
Btw is there a real life use for this? Like takinga function, fixing the removable discontinuous and get a new continuous function out of it. Does it have some practical uses?

>>7711103
Its the free microsoft calculator, but thats close to asymptote so it explodes near that point

>>7713046
Thats not the definition of sine, its usually defined IN THE CONTEXT of a right triangle.

>>7720890
1×3×5×7 = 105
1×3×5 = 15

No

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>>7709400

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Can someone explain why I would ever need to do this?

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>>7730539

>>7730800
To get some practice on algebraic manipulation with concrete examples. Also it helps visualizing what does it mean for something to be on base 10. But either you are in middle school or just some faggot who thinks we should learn how to balance a checkbook instead of math.

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Can someone please explain how this function has infinitely many points of discontinuity : http://www.wolframalpha.com/input/?i=%28%28-1%29%5Ex%29%2Fx

>>7730937
dw solved it senpai

>>7709400
senpai pls

>>7730937

Depending on what the domain/codomain is, it is either a:

- meromorphic function (if the function maps complex numbers to complex numbers), which is a rational function of two holomorphic functions (well-behaved functions with well-defined derivatives at all complex numbers); or

- function with uncountably infinite discontinuities (if the codomain is R, the only possible domain is a subset of Z \ {0} - pretty easy proof).

>>7731018
If the function were only defined on the integers it would have isoleted points so it would be continuous everywhere.

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>Mathematica
How do I get simple values like in the widget at the top but with a higher degree of precision?

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What the hell, why am I not getting the same output as in the example even though I have exactly the same input? (NSeries[Exp[x], {x, 0, 5}])

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So, like why does everyone seem to think general AI is so far off and only exists if the AI is all encompassing? I mean can't you just use a layered system where you have a series overarching decision AI that chooses which specialized AI/algorithm to use for a certain task? Seems like something like that would have most of the necessary parts plausible in the next few decades or so.

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>>7709400
What kind of goggles are best for a regular old lab class? I still have fog problems with the $3 goggles I've been using for about 2 years now, plus they're not super comfy. Is upgrading worth it, or are all goggles like this?

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A couple of question that might be simple enough:
1. How would I go about calculating what the group [math]U(4)/SU(2)[/math] actually is?

2. Suppose there is an eigenvalue problem [math]T(x) = \lambda x[/math], where [math]T[/math] can be represented as an at most first order differential operator [math]d_{t} - A(x) [/math] for some function [math]A[/math] of [math]x[/math]. If I only want to study the topology of the spectrum [math]\left\{\lambda\right\}[/math], would it be reasonable to let [math]x \in M [/math] for some manifold [math]M[/math] and look at the one-parameter group of transformations [math]\phi_{\tau}[/math] that is generated by the function [math]A'(x) = A(x) + \lambda x [/math]? Would some nontrivial topology of the spectrum be manifested as some topological property of the diffeomorphisms [math]\phi_{\tau}[/math]?

>>7732539
your acos and aasin function are not recognizable, the correct way to write them is ArcCos[x] and ArcSin[x]

>>7715141
That's a question I was thinking when watching Star Wars VII.
*SPOILER WARNING*
>The "Thermal Oscillator" is presumably a giant, hyper-powerful capacitor that stores energy in the form of light, possibly with the same technology used by lightsabers
>If light has no gravity, then such a device could store unlimited energy as long as any flaws such as dust particles remove a fixed amount of light rather than a percentage of the light
>If light does have gravity, then the device could store a still huge amount of energy, but not a sun's worth as the gravity of the beam would tear any equipment to shreds

>>7714835
Riemann sums are the definition of the riemann integral. You need them to prove the fundamental theorem of calculus is correct in the first place, which I assume is what you meant by "definite integration"

>>7732672
I got it figured out, I also wasn't loading the NumericalCalculus package. First time using Mathematica, it was a steep learning curve but it was well worth it. I ended up using MiniMaxApproximation instead of NSeries because it gave much better results over an interval. Thanks anyway!

>>7732582
Headstrap goggles are for babies who can't be trusted to not take them off every 5 seconds.

Get a set of these: http://www.amazon.com/3M-11329-Virtua-Anti-Fog-Glasses/dp/B00166OALC/

>>7715141
>Does this then mean that a beam of light travelling through the universe will bend spacetime like if there was a massive object moving there? Would a laser beam from a laser the size of a galaxy make stars and planets fall into it when it moves past them?
In GR the effects on gravity depend on relative speed, so the light wouldn't have an effect identical to passing massive object.

>>7709400
Let's say there's a global thermonuclear exchange and shit is fucked. Lots of people hide in fallout shelters or whatever, many more people just die or get horribly irradiated (and die soon after).

How long would the people in the fallout shelters need to chill underground until it's safe for them (or their descendants, if it takes -that- long) to walk about on the surface again safely without having to worry about radiation too much? Like, Strontium-90 has a half-life of like 30 years, right? Given how much Strontium-90 gets thrown about by a nuke, how many half lifes is it gonna have to go through before we're not too fucked? And what about the other common fallout particles?

>>7716682
>area squared
Solid angle.

>>7724735
>mandatory first year libarts seminar bs
>sjw prof
>wage gap myth
>provide the paper that closes the gap to 95/100 by accounting for relevant variables besides gender in class discussion
>make term paper very conciliatory but dont brush under the rug the obvious empirical evidence/observations that intersectional critical theory fails to explain
>get a B

If I quit masturbating will I be able to grow a beard? I've heard it gives you more testosterone.

>>7732863
A general tip for mathematica, if the function you use is blue that means it is not defined, so if you want to use an existing function write it and see if it's in black.

What is the name of this symbol[math] \mathcal{F} [/math] ?

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I'm trying to get into maths, but I'm having serious problems with basic, high school level combinatorics, are there any good books that will help me understand it intuitively?

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Why do gram-negative bacteria have an outer membrane but gram-positive bacteria do not?

>>7733362
(mathcal) F ?

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How do you do this?

>>7733658
tan (37) = ? / 3

? = 3 * tan(37)

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>>7733668
But that didn't work?

>>7733672
You either messed up the calculation or entered the answer wrong.

>>7733672
Did you round before multiplying by 3?

https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#safe=off&q=3*tan(37deg)

>>7733681
>>7733678
Oh, calculator was set to use radians rather than degrees.

If prisms refract light into strips of color, and the spectrum is so large that, if stretched from NYC to LA visible would take only a penny's size, do the other invisible light types wrap around the room hundreds of times?

>>7722905
Just call the guys in charge of scheduling and beg if you need the classes to graduate. They usually make exceptions

Which elective to take

Linear Optimization
>Linear programming modelling. The simplex method and its variants. Duality theory. Post-optimality analysis. Applications and software. Additional topics may include: game theory, network simplex algorithm, and convex sets. Couse topics: Theory and applications of linear programming, geometric and computational considerations, networks, applications of duality. 1. Linear Programming. 2. The Simplex Algorithm. Tucker Tableaus. The simplex algorithm for maximum tableaus and minimum tableaus. Cycling. 3. Noncanonical Linear Programming Problems. Unconstrained variables. Equations as constraints. 4. Duality Theory. The dual simplex algorithm. Complementary slackness. The duality theorem. 5. Application: Matrix Games.Linear Programming formulation of matrix games. The von Neumann minimax theorem.

or

Modern Mythologies in Mathematics
>You tell people that you are taking math classes, and they say, You study math, you must know a lot about . . . " But even after having succeeded in all of the lower-division courses, calculus and linear algebra, many students are not aware about how this math actually impacts the world around us. But modern life really does rely on technology and hence, the mathematics that is the quantitative foundation that makes it all work so amazingly. For example, chaos theory is often used to explain the complexity of weather forecasting; Fourier theory forms the basis for modern signal processing; and Google was born from the largest linear algebra problem ever conceived. This course builds from two popular books about math in the real world, In Pursuit of the Unknown: 17 Equations that Changed the World, by Ian Stewart and 9 Algorithms that Changed the Future: the Ingenious Ideas that Drive Today's Computers, by John MacCormick. But we will dive deeper, and experience in more detail how our knowledge of the calculus and linear algebra ts into these popularized narratives.

>>7734096
Lin Opt

>>7709440
depends what schools are in your state and what you wanna do when you grow up

Say that I place a flat circular sail of surface area x in an atmosphere of density y, and the updraft from the meeting point of the Hadley cells is z.

Is this a simple calculation, where thrust = xyz?
Or do large values of x result in air that wants to move up being trapped, meaning that the calculation would be more like yzx^w?
I'm having some fun studying atmospheric colonies, and I'm wondering if the heavier than air variety is viable. Sadly,

>>7734957
>cutoff
Touchscreens are fucking

Yesterday I tried one balloon of nitrous oxide and have felt very minor twinges from time to time in my arm since, should I be worried?

Question:
Does anyone know the name of those flat 2D paper models that you can open and it forms a 3D shape?
Is there any developed "science/math/art" to making those?

>>7735096
A net?

>>7735105
I don't know what a net is. But the remarkable thing is that you can store it in 2D (ie it just looks like a flat piece of paper) and anyone can just pull it up and the shape forms on its own.

I'll go ahead and lurk to find out myself, but is this board any good, or is it reddit-tier shit where you romanticize the concept of science and do fuck all.