/sqt/ Stupid Question Thread

>>8383404
Define failure.

http://www.cpp.edu/~engineering/ECE/documents/CPE_15-16.pdf

https://www.cpp.edu/~sci/computer-science/docs/SCI_Comp_Sci_2016-2017_VML.pdf

I think I fucked up. I just transferred from a community college this semester and realized that the curriculum of computer science just seems far more interesting than computer engineering. I'm specifically talking about the elective courses in computer science. Many of those elective courses seems to be what I want to do. What should I do?

>>8383412
Transfer again next year? They would probably let you switch that semester if you realized this soon enough, but seeing as its like 6 weeks in already you're probably too late. I'm also assuming your science/eng departments only accept once a year like mine.

You got into one so you can get into the other, its just up to you if its worth the time setback.

How much mass does an average comet lose to evaporation per orbit?

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Can anyone tell me how they got the Volume and Density?

>>8383404
>Is Elon Musk a failure?
Well that is a stupid question obviously. Because the answer is clearly maybe.

Serious question:
Are dinosaur bones and human made up of the same composition? If yes, why do we have so many dinosaur bones from millions of years ago but can't find many homo species bones who supposedly lived closer to our time.

Is this accurate?
https://answersingenesis.org/archaeology/ancient-technology/stone-tools-from-the-early-tertiary-in-europea-contradiction-to-any-evolutionary-theory-about-the-or/

Beginners chem student here,
How do I learn to distinguish what is a strong base/strong nucleophile from strong base/weak nucleophile etc?

I find it easy to identify strong/strong and weak/weak just by memorising the patterns (weak/weak is pretty much anything that ends in OH and or water for example) but would really like to understand the rest better.

I tried reading up on the Lewis or Bronsted definitions of bases to try and help. Althought I can memorise the definitions, I obviously don't understand it because it can't help me answer what is a strong/weak or weak/strong.

I have a first class ( 4.0 equivalent ) degree in physics from a top 20 UK university, what are my chances of getting a graduate scheme in a decent US university?

>>8383648
Yes essentially. Dino bones were conserved in fossils or peat bogs.

What computer science jobs are well payed, exiting and rich in variety?

>>8383648
Because the word dinosaur designates a much larger group than the word homo.

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Hey guys, how the fuck do I do equations like c) and d)[first ones] and to simplify a~e? Do you guys know any book or place I can read how to do them? I'm really bad at equations that have squares and any book that I have read only teach the simple ones that is easy as fuck but then give exercises that I have no fuck idea how to do them.

>>8383899
You only need the laws of square roots and apply them till you get the answer.

c) and d) are solved by knowing that sqrt(a*b)=sqrt(a)*sqrt(b) (this is also true for an arbitrary root)

Most of it comes down to intuition and that is nothing any book can teach you.

I might just be brainfarting here, but it's regarding a physics problem I was doing the other day:

I had car A and B a distance x apart. Each moving with different velocities and different acceleration towards eachother.
Could the time until collision be modelled as a single car moving with speed and acceleration equal to the sum to that of the two seperate cars(as if they were moving the same direction) a distance x until it hits a wall?

>>8383945
Yes in classical physics this is definitely possible. Just solve for the equation of motion of each car, then the difference between the two functions is the distance between the two cars. This can then be differentiated to get the velocity and acceleration of the new car traveling toward a wall. It gets more complicated at high speeds and high accelerations because relativity needs to be taken into account, and each car will have their own perspective that may not agree with the other about what they are "feeling" during the motion.

>>8383621
Volume: It's a cylinder, so use the formula [math]V=\pi r^2 h.[/math]

Density: Divide the mass by the volume.

Is there a difference between [eqn]A \overset{\tilde=}{\longrightarrow} B[/eqn] and [eqn]A \ \tilde= \ B[/eqn]?

What am I supposed to do if I'm just taking math courses for fun and all my local community colleges only offer up to ODE and I want to go further?

>>8384315
Read the wiki

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/sci/, help please, no idea how to solve problem like this one.

>>8384010
Isn't the arrow one a category theory relation.

What you need to write is:

$$ \forall x: A, y: B, x = y $$

for them to be equivalent.

>>8384322
calculated how much alcohol is in 12 cm^3 solution after that solve (alcohol cm^3)/(x+12cm^3)=20%.

(alcohol)/(alcohol + water) is the percentage of alcohol in the complete solution.

I got 9, 30 and 72, correct me if i am wrong.

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>>8383404
how many licks does it take till you get to the center of it?

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Guys, Do you know a good book of calculus that can help me with this?
(differential calculus I guess)
I'm on "Library Genesis" and got nothing

>take class in computational linguistics
>really like the course
>learn a lot
>it's group assignment based, final grade is based on performance on assignments which you work on with a group
>group consists of a bunch of slackers that waste meeting time with bullshit
>the guy that is supposed to submit the assignments (assigned on the first day, not changeable) always submits it late, automatic -40% off total assignment mark
>spoke with sessional professor about it, he told me to just deal with it
>ask if I we can change the assignment submitter so that I'd be the one submitting it, sessional professor says no
>end up getting a B- in the course because group is so terrible
>make projects in nlp on the side

Do you guys think it's possible for me to get a volunteer research position in nlp at the computational linguistics lab at my school?

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>>8384419
kek which shitty college do you go to? it sounds like they treat you like you're in highschool/a daycare

>>8384010
The first tells me that the arrow between A and B is an isomorphism (I'll be lazy and think in some pet category) and the second one simply says that the two are isomorphic without indicating in which way they are isomorphic.

>>8384411
This is pretty basic. Stewart or something should do fine.

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>>8384516
>This is pretty basic.
Yes, i know ;_; even in a quick search en wikipedia I find something. The only problems is my teacher is a fucking perfectionist. Everything has to be perfectly explained, even in the minor details. That frustrates me.
>Stewart or something should do fine.
thanks bro

>>8384419
Consider yourself lucky to have a comp linguistics course. That sounds badass.

What is the significance of 99% DNA shared between Chimpanzees and Humans? DNA only gives you what you are supposed to look like and how the body works right? Since Chimpanzees have similar structures they have very similar DNA.
Why is this touted as proof of evolution though. Sorry, if this is a stupid question

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>>8384816
you should think of evolution as a branching process

we are close enough (via common ancestor) to chimps to have 99% similarity

>>8384823
So does the similarity decrease going from Gorillas to Orangutans to New World Monkeys?

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>>8384827
im just a mathfag not an evolutionary biologist but it seems that way:

>Humans and gorillas differ in just 1.75% of their DNA, making our genomes more similar than previously thought. That percentage actually drops to 1.37% when compared to chimpanzees, our closest living relatives—but 15% of the time, gorilla DNA is actually more like human DNA than chimp DNA is, the Los Angeles Times reports. That "tells us that there are individual genes for which, if you want to find the closest sequence to humans, you won't necessarily look at chimpanzees. In a few cases, you'll look at gorillas," says a geneticist.

>>8383404
Not really a science question

When you integrate x^2.5 , you apply the rule

x^n+1
--------- ; n being 5/2
n + 1

The answer is 2x^7/2
---------
7

Where does the 2 come from that multiplies both sides lads? I just don't get it

>>8384931
x^n integrates to [x^(n+1)]/(n+1)

so if n=5/2 then

x^(5/2) integrates to
x^(7/2)/(7/2)
x^(7/2)*(2/7)
=(2/7)*x^(7/2)

>>8384936
Right on, thanks a lot, didn't get that it came down to something as simple as that

Couldn't we hypothetically synthesize any quantity of any material by modifying the atomic/molecular structure of raw materials on a microscopic level? I mean in a very distant future where this technology is available.

I don't actually know shit about science and this is my first post on this board.

>>8384953
kys this instant

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>>8384953
lurk more brainlet

>>8384961
I want planning on it but I want to know the answer to my stupid question first.

>>8384965
*was planning on it

I need to solve this inequality. [math]x/(1-x^{2}) - 2/(x+1) > 0 [/math]

I've taken a look at the solution but I'd like extra insight and a step by step approach would be helpful.

>>8385088
bring it to a common fraction

multiply both sides by the denominator, be sure to split into two cases, one where the denominator is negative and the other where it is positive, because this will change the direction of the relation

that's pretty much it

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anyone want to take this with me? its free and starts monday https://www.coursera.org/learn/modular-forms-jacobi

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Is this accurate?

>>8385120
Too advanced for me probably

If each cell has 3billion base pairs. and if there are 38 trillion cells in the average human body , does that mean we have 38 trillion x 3 billion base pairs in our body?

>>8385129
more if you count viruses, bacteria, and mitochondria

>>8385121
no. it's not even clear what they mean by information loss most of the time. is it less DNA as a whole? polyspermy is possible in many (usually plant) species. is it the loss of what was previously encoded in the region? well sure, but then why isn't the newly encoded gene a gain in infomation? Does it even matter if a beneficial trait is gained through a loss or gain in information?

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>>8385127
>To follow the course one has to know only elementary basic facts from the theory of modular forms (for example, the paragraphs 1-4 of the chapter VII of Serre’s “A Course in Arithmetic” are enough).

http://www.math.purdue.edu/~lipman/MA598/Serre-Course%20in%20Arithmetic.pdf
pic related is too advanced 4 u?

>>8385137
This is the closest thing to a grounded explanation I could find.
http://creationwiki.org/New_genetic_information

This might come off as a "brainlet" question, but how much mathematical knowledge would one need to start publishing papers, and how would one do it?

>>8385190
you need enough knowledge to come up with a new result, this amount of knowledge will depend widely on what field you're working in and what problems you're trying to solve

most likely you would need to study number theory and geometry for a decade before proving birch swinnerton dyer conjecture, but someone could easily publish some result in combinatorics within a year or two if they were lucky

How does Something come from Nothing. I've read alot about this but with no satisfactory answers. Hoping someone here explains it better.

>>8385215
N = Nothing

2*N = Something field over N nothing.

F(x) = 2*N

N : 2N -> S

>>8385166
that page has two definitions
new codes: claims all new genes must take the place of older genes. They themselves cite why it's wrong, as insertions can happen. Apparently this doesn't count though because the original function of the protein will probably be disrupted, which is not necessarily true. Even when a protein is partially disrupted, why is partial disruption equal to a brand new function? If your skin doesn't produce as much melanin but you can now see ultraviolet light is that not a gain in information? You also don't need to disrupt the gene at all, simply change its expression encoding. Old world monkeys are immune from hiv due to an over-expression of an enzyme. PEPCK-cmus mice have super endurance capabilities due again to an over expression.

side note: mexican tetra lost their eyes this way, so new information can be harmful. This was a net benefit for the fish as well though, so long as they keep living where they are.

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>>8383404
Does time even exist (outside of our imagination)? If it does, can you prove it?

>>8385215
"Nothing" includes "no physical laws" or else there'd be "something" (e.g. the physical laws)

No physical laws means nothing preventing something from coming about spontaneously, such as a bunch of universes with a bunch of random versions of the laws of physics that mostly blink in and out of existence until (and conceivably even after) some stable configuration is happened upon

What is the proof that the planets in our particular solar system formed out of a protoplanetery disk around the sun? I am aware of that we can observe solar system formation in different stages around the universe but what proof is there that the planets arose from matter rotating around the sun.

>>8385383
>I am aware of that we can observe solar system formation in different stages around the universe but what proof is there that the planets arose from matter rotating around the sun.
It's hard to know how to answer this question without knowing what sort of doubts you have in mind in particular.

>>8385431
What proof is there that the Earth didn't just pop into existence .

>>8385451
The dog that didn't bark.

>>8384419
Jesus Christ how horrifying.

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>>8385242
So basically specialization, then?

Is there a healthy alternative to coffee when it comes to getting energy? I feel sluggish since starting school and can''t bring myself the energy to study due to tiredness.

If you drilled a hole in the earth directly down until the opposite axis and jumped into it, what would happen? Would you have enough velocity to reach the other side?

>>8385589

gravity and drag would eventually bring you to a standstill at the centre, rotating as our planet does

>>8385589
Nah. Air resistance the whole way.

>>8385568
green tea also has caffeine. bout half that of coffee.

The definition given for the power of a signal is:
[eqn]\lim_{T\to\infty} \int_{T/2}^{-T/2} |g(t)|^{2} dt[/eqn]

But for even zero mean periodic signals (like cos(x)) this limit clearly doesn't exist. Everyone just glosses this over with no explanation so just what the fuck is going on here?

>>8385357
Depends on if you believe math exists as part of our universe, invented, or just imagined. If v=at, then t=v/a, so time is (change)/(rate of change)

>>8385121
No. What do they use to measure the magnitude of genetic information? Chromosomes, exons, base pairs? A salamander has a far larger genome than a human.

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How the fuck does quantum entanglement work

It defies the entire relativity theory that physics is built upon

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>>8385121
Or this?

>>8385597
sure the limit exists for cos(x)
its inf

>>8385653
sorry, I missed a term:
[eqn]\lim_{T\to\infty} \frac{1}{T} \int_{T/2}^{-T/2} |g(t)|^{2} dt[/eqn]


after going through the calculation what's left is roughly:
[eqn]1 + \lim_{T\to\infty} \frac{sin(x)}{T} = 1[/eqn]

which obviously exists and converges absolutely, so the problem was a figment of my imagination all along/

>>8385597
> The definition given for the power of a signal is:
Wrong. It's:
[eqn]\lim_{T\to\infty} \frac{1}{T} \int_{T/2}^{-T/2} |g(t)|^{2} dt[/eqn]

Without the 1/T term, it's the energy of a signal, which for a periodic signal is infinite (constant average power multiplied by infinite time).

>>8385809
>re-answering a question 2 hours after the mistake has been corrected and the solution posted by someone else
(you)

>>8383404
>not terrible melee weapons can carry you
Bullshit.

>>8383658
Small, unhindered molecules with high electronegativity are usually good nucleophiles.
Instead, if you want to know if a molecule is a good base you have to consider the pKa of the conjugate acid. (or, more widely, just the corresponding protonated molecule)
Sometimes (often) the two properties coexist at the same time. To avoid this, we pick a hindered negatively charged molecule, leaving the basic property but not the nucleophilic one.

e.g.
NaOMe good nucleophile/good base (MeO- is small)
NaOtBu bad nucleophile/good base (tBuO- is hindered)
Another very strong base is LDA (lithium diisopropylamide), where the two isoprpyl prevent the nucleophilic behavior.

A different example is NaH vs NaBH4 or LiAlH4. While the first is a strong base/weak nucleophile, the other two are weak bases/strong nucleophiles. Here's the reason lies behind the structure and the difference in electronegativity between Na and H in one case and B and H / Al and H in the other two.

For neutral molecules the base/nucleophile behavior follow the same rules. A simple amine may act either as base or nucleophile, but if I just want the basic behavior, I'll use a hindered amine (e.g. N,N-diisopropylethylamine).

But what if you just want the nucleophilic behavior and not the basic one?
Some molecules, such as F- (AgF is used in this case) act only as nucleophile.
What you actually do when you perform a reaction with a nucleophile, and you are worried about the fact that it may act as a base as well, you just look at you starting material and ask yourself: is there a proton in my molecule that can be attacked by my nucleophile (acting at this point as a base)?
To answer this question you have to know the pKa of every proton in your molecule and the pKa of your [conjugate acid] nucleophile. If pKa(molecule) > pKa(nucleophile), then you are safe. (Otherwise you either use an excess of nucleophile or change something along the synthesis.)

Hopefully this will answer.

>>8385604
that picture is fucking retarded

>>8385604
http://motls.blogspot.com/2010/11/delayed-choice-quantum-eraser.html

I'm not amazing at maths, is there a site I can use where I can plug in a whole bunch of data points in (x, y) format and have it spit out the closest equation that matches the data?

The only ones I've found don't do anything beyond linear equations, which I can't use because the data doesn't form a nice linear graph.

>>8384823
>2016, still believing the evolution meme

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>>8386026
desmos.com has some statistics features, but you wouldn't necessarily know about them. you define the form of the equation with some variables and it'll try to match the data

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>>8386026
>>8386059
basically go crazy my dude

reported for underage b&

theyre both simmilar, since we're both vertabrates, the modern descendant of dinosaurs is birds, and we should have a straight line of evolution frossils from 100m years ago to now. iirc the most recent fossils are from a few million yeras ago. more than 5. since the dinosaurs have been around for longer than large mammels, there would be more deposits of their bones

now for fossils. fossils are bones that have been converted to a rock over time because of them being covered with a material that has hardened, such as dead plant matter which has turned to pear or tar but no so much that it has turned to oil. iirc the best way to make a fossil is for the carcass of the animal or plant to be left under limestone, which is a rock with good properties for fossilisation.

here im not sure if you really are able to understand or even want to, but il give you the benifit of the doubt that you can understand any of this despite your demonstration of enormous stupidity ill assume its not wilful and keep typing

the reason there are fewer mammel fossils is pretty easy to understand if you get one thing which ill now explain

the world was created 4 000 000 000 (1*10^12) years ago as we know it after a planetoid the size of the earth slammed into one the size of the moon. one of the two broke in half and turned into the moon and orbited the earth at around 100 000km away moving at a gradual rate until it got to the 360 000km distance it is now. at some point over that time, bacteria like life formed and learned how to absorb solar radiation through a chloroplast like organism. about 200 000 000 years (2*10^9) ago multicelular life evolved in the ocean and 50 000 000 (1*10^8) years after that, or a bit earlier, what we call dinosaurs appeared on land. they lasted through 3 geographic periods or 135 000 000 (1.3*10^9) years until 65 000 000 (6.5*10^7) years ago, a comet hit the earth near modern day america, causing a nuclear winter, which combined

Are mind maps worth it for Physics/Maths or nah?

>>8386145
oh this was in answer to >>8383648
by the way

with already-active global warning effect caused by increased carbon from the digestive tracts of the land and sea dinosaurs, tiped the climate over the edge and cause one of the great extinction events, and the most famous. It was not the greatest extinction so far, and was as bad as the current human extinction will be after another couple centuries (which is on track to be the fastest).
anyway, about 5 000 000 years (5*10^6) ago, an ape known as austropithicas (spelling sorry) evolved in africa and the rest is history... or geology, since recorded history started 5000 years (1*10^3) ago.
the reason there are no human fossils is because humans evolved 1 000 000 years (1*10^6) ago, and it takes at least 1-3 000 000 (1 to 3*10^9) years for a peat field to form, at which point human remains would either be gone or still in non-fossil form i.e like those remains found from 10 000s of years ago from the ice age or the one before last.

interesting fact, some believe that it was the end of the last ice age that brought about civilization around the world, possibly because of a cultural change affected by the changing climate.

if you're wondering what the notation ive been using is here (1*10^9) then you should ask your parents or science teacher, assuming you go to school and aren't already working on the farm for your pappy at the tender young age of 11. not that individuals own farms anymore anywhere outside of india.

>>8384344
1cm^3 = 1ml container for 1g of water or less for thicker more for thinner liquids.
.35*12=4.2ml alcohol
.65*12=12-4.2ml = ??
.2*12=2.4
4.2/2.4 = 1.75 the ratio of 35% to 20%
1.75*12 = 21
21-12 = 9

just incase you actually have a competant teacher.
naturally there are multiple ways to do this with year 8 calculus.

>>8384816
>>8384823
someone did an experiment where they grew a human ear on a mouse... or maybe it was sewed on idk

anyway, it is a fact that if you insert human dna telling a monkey to grow an ear on its arse, it will grow a monkey ear, not a human ear.

being a programmer i think of it as identical functions with differnt paramaters that control how the body will look like.

i heard they say most of our dna is for fighting disease, but im not sure how true that is, though i do know AIDS came from monkeys, but even that is a rare disease that can cross species

>>8384816
>Why is this touted as proof of evolution though.
if you saw a computer on an alien spaceship, and it was running windows 7, would you suspect ab or c, or d?
that:
a the computer was put there by a human
b the computer was given to or stolen by the aliens
c the aliens developed it based on human computers for some sciencey reason

d the aliens have a parrel company called microsoft and a parralel coutry called america that also develops windows 7 PCs

i think any other possibility would be insanity, but highly possible considering the various inanities that humans hold and call "beliefs"

anyway, if you see two things that are simmilar to the trillinth decimal place, and were told to fix a problem and you could use anything to fix them, you would assume theyre from a common origin and not discount that origion without an equal ammount of evidence. epistemologicaly we can deny reality itself, but that would be the level of proof you would need to prove this alien windows computer not of human origin.

im not saying you have to believe it is, especially if the aliens tell you so, but if no one else saw the aliens, you cant expect people to believe that you found an alien computer with a dell symbol on it running windows 7 as proof of aliens.

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>>8385121
AHAHAHAHA AHAHA AHAHA AHA AHAHA AHAHAHA wut dafqu >o<

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>>8383404
how do I solve this?
>for step 2 I get (1,0,-1)-0

>>8386211
show your work and I'll show you what you did wrong

>>8386221
for u2*v1 I get 0

>>8384953
if troll 11/10

Explanation of how to solve this?

[math]|2-3x| < 4 [/math]

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>>8386277
http://www.wolframalpha.com/

>>8386277
Don't listen to this faggot >>8386284.

[eqn]\left| 2 - 3x \right| < 4 \implies -4 < 2 - 3x < 4 \implies -6 < -3x < 2 \implies 2 > x > -\frac{2}{3}.[/eqn]

>>8386293
thanks but what do the arrows represent?

>>8386300
It's the step by step solution you bloody brainlet

>>8386300
Arrows mean "implies."

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>>8386304
>>8386307
jokes on you i'm not the original poster

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>>8386235
show your work and I'll show you what you did wrong

>>8386293
Can you explain the steps tho?

>>8386321
First, we turn [eqn]\left| 2 - 3x \right| < 4[/eqn] into [eqn]-4 < 2 - 3x < 4[/eqn]. This is because of the definition of absolute value: if [eqn]\left| 2 - 3x \right| < 4[/eqn] then [eqn]2 - 3x < 4[/eqn] and [eqn]-(2 - 3x) < 4 \implies 2 - 3x > -4.[/eqn] (where we divided by -1, in which case we must flip the < sign to a > sign)

Then we just get x by itself. Subtracting 2 from every "side" of the inequality gets [eqn]-6 < -3x < 2[/eqn], and finally dividing by -3 gets [eqn]2 > x > -\frac{2}{3}[/eqn] (again, we're dividing by a negative number, so we must flip the inequality signs).

>>8386346
thanks anon you're great

what is the most reasonable way to write the set of all odd integers including zero?
is [math]\mathbb{Z}\setminus 2\mathbb{Z}\cup\{0\}[\math] likely to cause ambiguity?

>>8386371
set-builder notation seems the least likely to be misinterpreted, then just assign a symbol to stand for this set

>>8384953
look up binding energy, brainlet

>>8385215
check out the CTMu

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What the fuck am I doing wrong? I checked and double checked and I don't see where I am screwing up? Is it something syntax?

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>>8386434
Same with this too. I feel like total brainlet

>>8386434
[eqn]12e^{\frac{5\pi}{3}}[/eqn]

you're giving it as [pi, -pi] instead of [0, 2pi]

>>8386317
I realised what I did wrong, thanks

If the earth is a sphere then how come people in Australia don't fall off the planet?

>>8386448
ahh I'm retarded. So [math]\theta[/math] should just be [math]\frac{5\pi}{3}[/math] in the orginial equation I posted?

>>8386436
also, do you know what i'm screwing up here?

>>8386434
>>8386436

you're making simple arithmetic/reading mistakes (w/r/t the problem statement). Take a break and come back later.

>>8386470
>also, do you know what i'm screwing up here?
there are two operations the problem is asking you to do

one is multiply, which you did

what is the other?

>>8386471

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How off is this?
https://answersingenesis.org/human-evolution/hominids/building-nutcracker-man-from-the-ground-up/

How do I evaluate this:

[math]\forall x \textgreater 0, \exists y \textgreater 0 : |x-2y| = 3[/math]

True or false and why? (latex might fuck up)

>>8386839
[math]\forall x>0, \exists y>0 : |x-2y| = 3[/math]

>>8386844
Cauchy-Shwarz

help
>all vectors v ∈ V so that vT(0,1,1,−2) = 0.
> What is the dimension of V and find a basis of V

>>8386844
True
y=x/2+3 > 0 satisfies it for all x>0

So my family has a story of hemorrhoids, and after a bowel movement I found little blood on top of the stool and a little in the toiler paper
This is the third time in 8 months, should I be worried?

>>8386315
ur still a MONG, u

>>8386930
>forgot to add for r 4

I have no idea about biology and I would want to learn about telomere research.
What should I read and how can I start?

Not a stupid question but dont want to make thread atm, maybe tomorrow.

Im looking for a topic for a school research paper, estimate of 60 hours of work, with a short presentation at the end. Its basically my last school project, and if I pass I go to university.

Now I have the "science" profile, and am looking for an interesting topic. It can be physics, chem, maths. Theres lists of what others picked but its so generic and I just dont want to do something Im not interested in. Anything new and relevant maybe? I thought about chemistry in cooking, as in for example what the perfect steak would be, but im uncertain. Im already over due bc i dont want to pick something I have no interest in.

Any medfags here? I was diagnosed with cancer this week and I'm freaking out. I don't know if the doctors might try to scam me with some unneeded treatment.

>>8386059
>>8386064
Damn, this looks like exactly what I've been searching for. Many thanks.

How do I find the energy levels of a single particle in a given potential?

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Explain conditional probability for me pls senpai.

I understand that it is the probability A given B which sort of means that we are working with a subset of the sample S. But I don't understand on the intuitive level why P(B|A) = P(A and B) over P(A)

Please explain this chemical reaction to me like I'm a chemistry retard (because I'm one):

On the activity series, it states that:
[math]Potassium reacts with water to displace H_2[/math]

Doesn't this mean that when potassium reacts with water, the equation should be:
[math] K + H_2 O = KO + H_2[/math]?

I don't understand why the correct equation requires two of each reactants. H2 is literally sitting right fucking there, why do I need to multiply both by 2?

>>8387397
it won't make KO

>>8387373
> I understand that it is the probability A given B
B|A is B given A.

> But I don't understand on the intuitive level why P(B|A) = P(A and B) over P(A)

Note that B given A is the same thing as (A and B) given A. Given that A has occurred, if B also occurs then it means that both A and B occurred.

If you draw a Venn diagram "to scale" (i.e. the area of each region is proportional to its probability), (A and B) is the intersection of A and B. P(A and B)/P(A) is the ratio of the "size" of the intersection to the "size" of A. So if you throw darts at the diagram, it's the proportion of the darts which land in A also landing in B (i.e. in the intersection).

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>>8387373
>>8387373
try drawing a venn diagram

you have [A (A & B) B]
the probability of B given A, is as you say contained in the subset [A (A&B)] since you know A happened

now what's the probability of B happening here in [A (A&B)]? well it only happens if you're in A&B, so you want the portion of A&B inside of A: P(B|A)=P(A&B)/P(A)

how's ottawa these days?

>>8387411
I know that the right answer won't have KO in it, but I don't understand why that's the case. [math]H_2[/math] is right fucking there and the activity series literally says that the reaction will displace [math]H_2[/math].

>>8387422

>how's ottawa

i fucked up that one, didn't save after cropping. it's not cold yet.

>>8387417
>>8387422

thanks, the venn diagram was especially helpful, but I still don't quite understand why it's probability and not a set of event A.

Like you said using venn we are working with the subset A and inside that A contain some B. From what I understand, shouldn't we take the size of B then divide this by A? Or does P(A and B) over P(A) work because the denominator of both prob is the same so they cancel out?

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>>8387435
if you took all of the size of B then you'd be including the cases where A&B might not be happening together, i.e. B happening but not A

>>8387435
>shouldn't we take the size of B then divide this by A?
For elements in B that aren't in A this will be wrong, since it won't be prob of B -given- A

Think of the finite, uniform analog, now, maybe rolling a die. |(B and A)| / |A| gives the probability of B given A. For instance, let A be {1,2,3} and B be {2,3,4}. Then B and A is {2,3} and |(B and A)| / |A| is 2/3.
Now, this requires that every element of the sample space S={1,2,3,4,5,6} have equal probability, i.e. P(A)=|A|/|S| for every A. If this is not true in general (rolling multiple dice, rolling infinite dice and taking the average) so instead of |A| you want P(A). But it's the same idea

>>8383404
How do you relate 1-cycles in [math]H_1(X)[/math] and the members of [math]\pi_1(X)[/math] in path-connected CW-spaces? At first I thought that you can take 1-skeleton and then contract everything that 2-cells connect. But then I realize that it doesn't work, for instance, in torus you have two 1-cells connected by a 2-cell but both aren't contractible.

>>8387473
>>8387482

okay that obviously brainlet of me, I meant to say take the size of (A and B) then divide this with the size of A

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>>8383404
Now here's something that's not necessarily a question, but I'd be grateful to know if I was right.

Y'see, the shop Supreme was selling £30 bricks. 'Designer' bricks. So,the idea was formulated - Could we build a wall along the Mexican borderline, with these bricks.

My god-awful maths is in the picture. If I have failed to achieve even the most basic comprehension of maths, you might as well hit me with it.

>>8387397
>>8387424

Because, as already said, you don't obtain KO, but KOH.
Now, the reaction is:
[math]K + H_2O => KOH + H_2[/math]

and if you try to balance it, you obtain
[math]2K + 2H_2O => 2KOH + H_2[/math]

You can't understand/say how many equivalents do you need if you do not consider the right reagents/products.

>>8387424
KO isn't a stable species, so this is not a complete reaction.
The isolated product(s) would have to be K2O and/or KOH
Multiplying by a whole number is just bookkeeping so you don't write an incomplete reaction or report "half" a product molecule. Think about it, any KO formed will quickly react with more potassium metal or water and form something else, and you're interested here in what ultimately happens.
How exactly reactions proceed is something you'll do at a satisfying level later

>>8386469
Because the North Pole is actually the bottom

When discussing physical problems why is the partial derivative with respect to time excluded from the gradient of a function? wheras, from math class I understood the gradient to represent a vector containing the partial derivatives of all independent variables.

[eqn]\nabla f(t,\vec{x}) = \frac{\partial f(t,\vec{x})}{\partial x}\hat{i} + \frac{\partial f(t,\vec{x})}{\partial y}\hat{j} + \frac{\partial f(t,\vec{x})}{\partial z}\hat{k}[/eqn]

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What is the example of a cruve with no natural parametrization?

>>8387496
I got lost somewhere along the way, but I took a different approach an did wall_volume/brick_volume and got a total of 25,370,819,326 bricks needed, worth 761,124,579,779 dollars.

Also, you have to multiply by 18 to have a 2 meter wide wall. (2000/110=18)
If you do so, the result should be the same.

>>8387562
Awesome! Thanks.

>>8387547
Any non-differentiable curve

>>8387610
But how do I show that there is no reparametrization that natural?

>>8387628
You can show that at some point its derivative [math]\frac{\partial \gamma}{\partial t}[/math] cannot be a non-zero vector.

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>>8387641
try turning it around, it might be easier

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Hey back here again with some problem solving questions. Am I correct that player one will always win this game?

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>>8387646

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>>8387672
why dont you brainlets ever post us your thought process so we can tell you if you're right or wrong?

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>>8387672
I worked backwards from the top right square

>>8387682
>>8387687
Sorry was having trouble posting a picture from my phone. The file was too large to start and fml it's rotated the wrong way.

>>8387639
Yea, I was thinking about [math] |x| [/math],but should I show that all possible parametrizations of this curve are [math] \gamma (t) = (f(x),|f(x)|) \\ Domf=\mathbb{R} [/math]

Which obviously has a problem at 0

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>>8387673
wtf is the question you're trying to prove brainlet?

>>8387530
I am also curious about this. Hopefully someone answers.

>>8387697
If P_k(n) is the number of partitions of n into exactly k parts, and Q_k(m) is the number of partitions of m into k distinct parts, show that P_k(n) = Q_k(n + C(k,2))

>>8387672
manhattan distance always decreases by at least 1 each turn. If the longest path is chosen (decreasing manhattan distance by 1 each turn) then the player whose turn it is (namely, the first player) would lose. Therefore the first player should try to put the second player into a playing position with an even manhattan distance, which would be a diagonal move. But the same strategy applies in this case, as a diagonal move keeps the manhattan distance even. So the second player wants to move diagonally, too, to give the first player an even board. Thus they march diagonally down the board for a second player loss. If at any time a player chooses a move which decreases distance by 1, the other player responds by decreasing the distance by 1.

Note what happens on a 7x7 board...

Yep, [math]|\gamma'(t_0)|=1[/math] requires that some vectors among [math]\gamma(t)-\gamma(t_0)[/math] have strictly negative scalar product but it's not the case when [math]\gamma(t_0)=0[/math].

>>8387694
>>8387857

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Alright lads,

How the heck do I show if A and B are sets then, (express the difference of A and B as the intersection of A and the complement of B.)

A - B = A ∩ Bc

Here's what I got:
A - B = {x | x ∈ A ^ x (-∈) B}
={x | x ∈ A ^ x ∈ Bc}
= A ∩ Bc
Is that it or is there more??

>>8387530
> I understood the gradient to represent a vector containing the partial derivatives of all independent variables.
You can find the gradient with respect to whatever set of variables you want.

Essentially, some of the variables are treated as variables while others are treated constants for the purpose of the gradient.

The dimensionality of the resulting gradient vector will be the same as the number of variables.

So if you have a function of position (x,y,z) and time (t), if you calculate the gradient w.r.t. x,y,z, you'll get a 3-vector which is a function of x,y,z,t; if you calculate the gradient w.r.t. x,y,z,t, you'll get a 4-vector (i.e. the gradient direction is in space-time rather than just in space).

Most real physical equations have a bunch of constants which you wouldn't treat as part of the "space".

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>>8387892
that's it, you did it well

>>8387892

I'm just learning how to do proofs and this is how I feel most of the time. I'm not even sure if I've actually showed anything sometimes.

>>8383852
Depends on you and what you find exiting. If you live in a good city a CS degree will get you in anywhere you want.

>>8384315
look up a university's syllabus and texbooks they use online for higher math classes. Start working and reading the textbook.

>>8387899
Awesome thanks!
>>8387904
Lel yeah it seemed way too easy of a proof it made me unsure.

I'm trying to prove the Complement Laws as well. I think I've got it something isn't making sense

>A ∩ Ac = O
={x | x ∈ A ^ x ∈ Ac}
={x | x ∈ A ^ x (-∈) A}
From here do I just conclude its an empty set
=O

I feel like doing so is pulling something out of my ass

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>>8387912
this is basically just using the law of excluded middle. no element can both be in a set and not be in a set, so {x | x ∈ A ^ x (-∈) A} has to be the empty set

>>8387912
>I feel like doing so is pulling something out of my ass
This feeling is a big red sign that your proof is incomplete. In this case, your last step should have some more explanation. *Why* is {x | x ∈ A ^ x (-∈) A} equal to the empty set? To do this, you need to show there does not exist an x such that x ∈ A ^ x (-∈) A.

Or, since that's a fairly trivial result, you could just state that in your proof. In general, I think your proofs could benefit from more words. Explain how each step follows from the other. If you cannot say precisely why some statement follows from the previous one, then you know you're missing something. This will make things much clearer in your mind and will make your proofs easier to read.

I have to take a Functions math class for programming and analysis for college.

Is functions easy?

p.s: i fucking hate maths

>>8387930
>Functions

Huh? What, like basic algebra functions?

Fucking CS brainlet.

>>8387919
you sir are a gentleman and a scholar.

>>8387927
Really good advice here. Much appreciated. I wrote something along the lines of the sets never overlapping.

>>8387934

quadratic, trigonometric, and exponential functions

>>8387967
LMAO! Is this a joke?

Drop out of that school. Transfer somewhere else. And don't get a meme degree.

If you can't do that, then at least take a calculus course. This "functions" class sounds like a waste of time.

>>8387976

I'm not getting a meme degree, this course that teaches quadratic, trigonometric, and exponential functions is a pre-req for programming in college

How do I decompose cycles?

Like I can go from (1 2)(2 3) to (1 2 3), but not the other way around. Since (1 2)(2 3) = (1 2 3) there must be some way to get back but I can't seem to find a concrete example online for this

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>>8388136
it depends on how you want to decompose.

you can decompose into transpositions like that but its not very useful since it's not unique. for example:
(1 2 3)= (1 3) ( 1 2) = (1 2) (2 3)
i dont know which rule you use to specifically get (1 2) (2 3) but similarly consider
(1 2 3 4 5) = (1 5) (1 4) (1 3) ( 1 2)
you can see a bit of a pattern here in that you can always decompose as
(a1 a2 a3 ... an) = (a1 an) (a1 a_(n-1) )... (a1 a3) (a1 a2)

decomposition into disjoint cycles is unique though, up to permutation of the cycles, and is much easier to explain:
consider (1 2 3 4)(5 6)(3 4)
see where 1 goes, 1 goes to 2, so we start a cycle (12
where does 2 go? it goes to 3, so now we have (123
where does 3 go? 3 goes to 1, so we can close that cycle (123)

4 goes to 4, so you can write (4) or just exclude it
5 goes to 6 and 6 goes to so we have
(1 2 3 4)(5 6)(3 4)=(123)(4)(56)=(123)(56)

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If the current is going from left to right then does that mean that the electrons are going from right to left?

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>>8388136
>>8388161
oh i guess you can use the rule
(a1 a2 .... a_n) = (a1 a2) (a2 a3) (a3 a4) ... (a_[n-1] a_n)

>>8388161
Essentially I'm interested in finding out how easily I can undo these compositions. Surely there is information found in the composition process that I'm just not seeing while crashing cycles together

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>>8388217
is this rule not enough?
(a1 a2 .... a_n) = (a1 a2) (a2 a3) (a3 a4) ... (a_[n-1] a_n)

applying it to (1 2 3) gives what you want, (1 2) (2 3)

>>8388179

Also they can be pretty arbitrary, for example, composing (1 2 3 4 5 6 7)(6 8 9) yields (2 3 4 7 1)(6 8 5), which probably doesn't have a nice rule for going backwards

>>8388227
Oops, that should be (1 2 3 4 5 6 7)(6 8 4), not (1 2 3 4 5 6 7)(6 8 9)

>>8388166
Current is defined as rate of charge flow through the relevant cross-sectional area per unit time. So if you have a net positive charge flow to the right and your only charge carriers are negative, then you must have a net negative charge flow to the left.

So yes, electrons move opposite the direction of current flow.

>>8383404
What's the physics behind logic gates? Do they reserve electricity like capacitors do and use that voltage inside of it to output a 1 or 0?

>>8388136
For any two permutations P and Q, P⋅(P'⋅Q)=(P⋅P')⋅Q=Q and (Q⋅P')⋅P=Q⋅(P'⋅P)=Q (where P' is the inverse of P).

IOW, given Q, you can choose any permutation P and decompose Q into either P⋅(P'⋅Q) or (Q⋅P')⋅P.

So for a permutation of length n, there are n! ways to decompose it into the product of two permutations. More generally, there are n!^(k-1) ways to decompose it into the product of k permutations (i.e. choose any k-1 permutations arbitrarily, and the last one is uniquely determined).

>>8388491
No.

Consider how you'd build logic gates from relays. Two (or more) normally-open switches in series = AND gate. Two (or more) normally-open switches in parallel = OR gate. Normally-closed switch = NOT gate (inverter).

Practical logic gates use transistors (BJTs or FETs) instead of relays (and more complex circuits usually only use NAND gates). But there's no reason for them to store charge.

>>8388508
Oh right I forgot about the switches in parallel or series. But how do they close? For example 2 switches in series, if both A and B are 1, they should close to output a 1, how is that possible? Does it weigh the incoming electrons or something?

Question: Does explosive decompression in space actually happen?

I mean, the inside of a ship would have 1 atmosphere, while the outside would have 0. Would that not be like air moving from a 2atm container to a 1atm container?

Can namespaces in C++ be viewed as a type, in a technical sense, of variable signifiers?

which is the better place for units?
> 3.00 N * 10^10
> 3.00 * 10^10 N

>>8389017
> 3.00 * 10^10 N
That's not just the best place, it's the only place where you can put them.

>>8383404
Not really science but do you guys believe suicide is part of natural selection?

Not shitposting here, reply with only a sentence if you don't feel it needs more explanation, just curious on this specific question.

>>8386483
>>8386436
How did anon fuck up on this problem? I made the same mistake/got same answer...

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>>8389501
Does anyone know?

>>8389501
>>8389547
You didn't notice the conjugation bar above the expression.

>>8389552
What does that do?

When do I know when to use LaGrange multipliers or Second Derivative Test with a bounded set for finding the extrema of multivariable functions?

>>8389552
So does that mean the answer is [math]72-3i[/math]?

>>8389321
>Not really science but do you guys believe suicide is part of natural selection?
everything is part of natural selection that impacts reproduction and child success

I asked this /3/ this but I think it might be too technical to them. the subject is about rendering light transport with bidirectional vertex connection and merging. I figured at least someone on here might know.

I'm having trouble visualizing what vertex connection and merging is. Please tell me if what I think I understand is right.

>Have merging radius in each part of the scene
>Photon from eye and light source are fired out
>Photons bounce around until they hit anywhere within the same radius
>Both photons are then merged together to form a light path from the eye to the camera
Is this right?

And one more thing i don't understand is the merging radius. What exactly IS the radius and how is it scaled?

Also is VCM really only useful for scenes with specular-difuse-specular transport?

>>8387347
Anyone?

>>8387206
Why does water vaporize at enviroment temperature/atmospheric pressure?

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Guys, I need your help

>What does it depend the accuracy of Cp values (and hence the enthalpy) calculated from empirical correlations reported in the literature?

What does that mean? I don't understand.

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>go to Cal Poly Pomona
>take Physics 131, Intro to Electrical Engineering, and C Programming
>Get my first exam back from each course
>Fs
>28 years old
>transferred from a community college
>spent hours on those three subjects reading the notes and doing the problems
>still fail

Now what? This was my first quarter. Should I change majors or just quit all together? What's an easier major that is still employable?

>>8389955
Uhh, is it asking for what Cp values are dependent on? It'd be active degrees of freedom.

Are there any good youtube channels that you guys recommend for Electric Circuit Analysis Fundamentals?

>tfw got a bad grade even though I was very confident
>tfw professor grades harshly

I wanna git gud, I'm going to be doing some book problems, but I have no idea if I'm going to do them right or not.

What's a manifold?

>>8390683
a set which if you look closely enough at any point, looks like euclidean space (R^n)

>>8390686
So what's a manifold gasket?

I was thinking the other day It would be cool if you could have a bike with some gyroscope that had a lot of angular momentum and then you could flip it and change direction of your bikes momentum.

Would it be too inefficient or just impossible? I'm not sure how it works.

I'm applying to SDSU and some other cal states for computer engineering. SDSU doesn't require the last physics course (waves and optics) or multivariable calculus. All the other cal states I'm applying to do require them. Are these 2 courses necessary or useful for computer engineering?

>>8389970
Maybe the quarter system moves too fast for you. Can you take C programming and physics at a community college like IVC?
Also are the classes really that hard? What's intro to engineering about?

Can someone please explain to me when and why do the limits of an integral change?

I am unclear on that and would appreciate some guidance on this. Thank you.

You have a 2D complex vector space V, with basis vectors v1 and v2, i.e. any vector in V can be written as A*v1 + B*v2. Do A and B have to be real or can they be complex?

>>8391445
someone??

>>8391472
Simple answer: the fact that it's called a "complex vector space" means that the scalars you multiply vectors by are complex numbers. That's the definition of a complex vector space.

What may be a tricky bit is that C is not a 2D complex vector space. C2 is.
Since complex vector spaces have complex multiplication you can build C from just {1} (multiply by whatever complex scalar you want).

C is only only 2D if you don't allow multiplying by complex coefficients (only using real ones you can see you now need 2 vectors to build the whole space). But a space with only real coefficients is a real vector space, not a complex one.

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Why does the [math]a[/math] just disappear hear? can someone explain?

>>8391559
Notice how C changed to C1?

They used the log rule ln(ab) = ln(a)+ln(b) to pull out the 1/a from inside the log, but ln(1/a) is a constant so they folded it into C.

>>8391559

ln(u/v) = ln(u) - ln(v)

when you take out the ln(a) that's a constant and so it gets absorbed into the constant C which is why C becomes C1 in the second line

>>8391530
Let F be a primitive of f (F is a function where F'(x) = f(x))
If F exists (if f is integrable), by the fundamental theorem of calculus
[eqn] \int^b_a f(x) \, \mathrm{d} x = F(b) - F(a) [/eqn]
Then
[eqn] \int^b_a f(x) \, \mathrm{d} x = F(b) - F(a) = - [ F(a) - F(b) ] = - \int^a_b f(x) \, \mathrm{d} x [/eqn]

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Why is the hypotenuse for the triangle [math]1[/math] here?

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can anyone tell me how to find V2?

>>8391610
For adiabatic compression, you can use the formula

Pressure*Volume^n = Constant

You're given n, both pressures and the first volume. It's simple math.

>t.guy who got kicked out of engineering, remember to turn up for your group projects

Hey /sci/, how does an integral work?

As in, if I look at the definition of the riemann integral

[math]\displaystyle \int_a^b f(x)dx = \sum_{n=0}^\infty f(x_n) \Delta x_n[/math]

I have that n is a discrete variable, so we have a discrete infinity on the right side, but the left side of the equation requires a continuous infinity.

How come that when looking at each partition we don't skip any area from the real numbers in between?

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Math babby reporting in, much in need of help.

I have a basic understanding of the concepts of gradients and direction derivatives, but I can't figure these out. Can someone give me out? I'd really appreciate if you gave some intuition behind what's happening too.

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>>8391658
Read an analysis book it will help significantly with what you're asking.

Basically, your equation is wrong. The Riemann sums converge to the integral.
For every small number epsilon there is a partition that is coarse enough such that
[math] | I - R | < \varepsilon [/math] where I is the integral and R is the Riemann sum.

Attached is the (incomplete) definition from my notes. Hope it helps

>>8391658
[eqn]
\int_{a}^{b} f(x) \; dx = \lim_{n\to\infty} \sum_{k=0}^{n} f(x_k) \, \Delta{x}[/eqn]
Where [math]\displaystyle \Delta{x} = \frac{b - a}{n}[/math]. Hope you remember how to evaluate limits.

>>8391690
>For every small number epsilon there is a partition that is coarse enough such that |I−R|<ε where I is the integral and R is the Riemann sum
You mean fine enough.

>>8391708
Yeah. What he said.

>>8391607
I don't see a problem with the 1 but 2u seems incorrect since
[math]1^2 - \sqrt{\frac{1}{4} - u^2}^2 \neq (2u)^2[/math]

>>8389568
Not sure if I remember this correctly but the second derivative test should work for testing the interior points of the set.
Lagrange is used for the boundary. If there are points in the boundary where Lagrange method can't be applied you need to test those points manually.

>>8391690
I think I get it now

I guess that what I was thinking is something along those lines: If I look at the partition close enough to the point of every individual partition amount to a single number, then since the function is discrete, it would skip over the values, but since we're looking at the difference, then it doesn't matter.

But that begs the question, how do I define the area of a function on a discrete space?
I could simply use the difference, but would that even make sense?
As there is nothing in between the two values, with "continuous" sets like the reals, I know there are no gaps, yet with the discrete topology I can say that they are continuous, so how would it even make sense?

I'm confused as fuck

why do we like the things we like?

for example me:
until now I listened to a music genre that I grew up with, but a few weeks ago I got into another genre and I'm really confused, because I don't know why.
I didn't like it before, it doesn't "fit" to me, at least others would tell me that I don't look like someone who likes that kind of music

so why is that
why do I suddenly like something without being influenced

why are there other people who like the same thing that I like, when we have NOTHING in common

my head hurts

>>8391736
Where does the 1 come from? can you explain please?

>>8387930
What this guy said>>8387976

There is no way in the world you can spend an entire semester on what you just described.

>>8389289
Not really, you can always multiply a dimensionful quantity by a dimensionless one.

>>8391666
a: find where they intersect, take the gradients of both curves at that point, and then calculate the angle via cos(theta) = <x, y>/|x||y|.

b: hint: the normal is perpendicular to the gradient

>>8391974
anyone????

>>8392125
pythagorean theorem

Does anyone know of a resource for familiar measurements? I'm looking for a list of comparisons of SI units to common everyday things. For example, 1 MeV is the amount of energy required to power n homes for 30 days, that sort of thing. I'm apparently failing at Google today.

>>8392137
I know that's what they use, but I don't see how they computer 1. Can you please explain?

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How did they expand [math]\sin(4\theta)[/math] like that?

>>8392198
apply double angle formula iteratively

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It technically doesn't matter which leg I assign [math]w[/math] and the other one that I assign [math]\sqrt[]{4-w^2}[/math]

>>8392208
right?

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Can't figure this one out.

Any ideas. From playing the game it seems player 1 has the advantage, but I can't come up with a surefire strategy.

>>8392232
Go first
Always take as many as you can without exhausting the row

>>8392294
Yeah but if you take two from the third row and the second player takes two from the second row you lose.

>>8392232
Any idea how to do this? I know it's basically a nim game of 1, 2, 3 but I really don't understand how nim sums and stuff works after reading about it.

>>8392232
First person to play loses.

Current state is 1,2,3. The first player can change the state to any of:
0,2,3
1,1,3
1,0,3
1,2,2
1,2,1
1,2,0

For each case, the second player's responses should be:

0,2,3 -> 0,2,2
1,1,3 -> 1,1,0
1,0,3 -> 1,0,1
1,2,2 -> 0,2,2
1,2,1 -> 1,0,1
1,2,0 -> 1,1,0

TBC.

>>8392408
This leaves the first player with one of two states (swapping rows changes nothing): 0,1,1 or 0,2,2.

For 0,1,1, the only moves are to 0.0,1/0,1,0; the second player takes the last piece and wins.

For 0,2,2, the available moves are:
0,1,2
0,0,2
0,2,1
0,2,0

0,1,2 and 0,2,1 are equivalent, as are 0,0,2 and 0,2,0.

For 0,0,2/0,2,0, the second player takes both pieces and wins.

For 0,1,2/0,2,1, the second player takes one piece from the row with two pieces to leave 0,1,1, which as seen above is a guaranteed loss for the first player.

how does one "do" science?

i mean i already fucking love it, but how do i "do" it?

>>8392387
> I really don't understand how nim sums and stuff works after reading about it.
The question specifically says that you're not allowed to use theoretical results about the game in general (i.e. nim sums).

>>8392416
You don't.

Why does nordazepam have a longer half-life than diazepam? Is it more lipophilic or is solely because diazepam is also metabolized to temazepam at the same time which has a much shorter half life so diazepam is only eliminated faster because it has more ways to be metabolized?
Demethylation should make it less lipophilic right? Not by much but still somewhat?

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I'm doing Serge Lang's book, and now I stack on some exercise(pic)
Ok, i tried to reduce system (a):
ax+by=1 | * d
cx+dy=2 | * b
It equal to: dax-bcx=d-2b
x(ad-bc)=d-2b (and as we know from title, ad-bc != 0)
So we can represent ad-bc as "k"
xk=d-2b (where k!=0)
Thats it? Should I do something else? How?

>>8392193
>>8391736 said it's wrong, so it comes from their ass

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>>8392525
Oh, i got this
In theory part,he said that in ex.9 I should I proof that solution exist, so from my reducing I got:
xk=d-2b
x=d-2b/k!=0, and that should make sense, 'coz that implies existing of solution.
Am I right?

>>8392525
You also need to solve for y.

ax+by=1 | * c
cx+dy=2 | * a
bcy-ady=c-2a

=> x=(d-2b)/k, y=(c-2a)/k

>>8392533
A solution exists when the determinant (ad-bc) is non-zero. If it's zero, you can't divide by it.

In the general case:
ax+by=p | * d
cx+dy=q | * b
(ad-bc)x=dp-bq => x=(dp-bq)/(ad-bc)
ax+by=p | * c
cx+dy=q | * a
(ad-bc)y=aq-cp => y=(aq-cp)/(ad-bc)

Thus for any a,b,c,d,p,q, you can find x,y so long as ad-bc is non-zero.

If ad-bc=0 => ad=bc
divide both sides by b => ad/b=c
divide both sides by d => a/b=c/d

Which corresponds to the lines ax+by=p and cx+dy=p being parallel. If p/q=a/b=c/d, they're the same line, meaning that there are infinite x,y pairs which satisfy the equations (i.e. infinite solutions). Otherwise, they have the same slope but different offsets, so never intersect, (i.e. no solutions).

What's the math construct I'm looking for?

I want to know, if I flip a coin x times, how many ways can I get a pair? Example, if x = 3, I can get no pairs:

H T H

And I can get one pair, two ways:

H H T
T H H

Thus, answer is total of three. It does not matter whether a "pair" is two heads or two tails.

It's easy at this scale, but when you start being able to fit three different pairs in I have no idea how it works.

>>8392626
Binomial distribution?

>>8392641
I actually played with that but couldn't seem to make it produce the right output.

is there a formula to find a square root exactly?

>>8392719


float Q_rsqrt( float number )
{
long i;
float x2, y;
const float threehalfs = 1.5F;

x2 = number * 0.5F;
y = number;
i = * ( long * ) &y; // evil floating point bit level hacking
i = 0x5f3759df - ( i >> 1 ); // what the fuck?
y = * ( float * ) &i;
y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
// y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed

return y;
}

>>8392719
> is there a formula to find a square root exactly?
Define "exactly".

The square root of a rational number isn't, in general, rational.

It's fairly straightforward to find the closest rational approximation with a given denominator. So e.g. for a fixed-size floating-point representation, you can reliably find the closest representable value.

>>8392726
That doesn't find the square root (or even an approximation to it). It finds an approximation to the reciprocal of the square root (which is what you want for normalising vectors, as multiplication is cheaper than division).

>>8392626
You have [math]2^2[/math] ways to choose H or T in the expression - XX

HH
HT
TH
TT

The answer is [math]\frac{2^2}{2}=2[/math]

You have [math]2^3[/math] ways you can choose H or T in the expression- XXX

HHH
HHT
HTH
THH
HTT
TTH
THT
TTT

Now there is 4 cases, HHT, THH, HTT, TTH. Are HHT and THH different pairs? If
so the answer is [math]\frac{2^3}{2} = 4[/math]. Otherwise the answer is yet again 2.

>>8392747
>Are HHT and THH different pairs?

Yes they are, and oh god, thank you for making this happen.

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Calc 4 question here. I understand how to get y1 through 7, but I can't remember how each part translates into the particular solution (?) Y. I'd forgotten to bring my notebook to lecture and had to write it on the back of some old homework.

>>8383404
>avoid the ruins
>free estoc and fire keeper soul

Can I get any help with this:
A.
Your system consists of 10 physical nodes connected w
ith a redundant
network. The system is designed in such a way that all nodes must be
running for it to provide service.
Each node has a probability of failure of
1% in a given month, and it will take about 6h to fix a failure (or replace
a node). Estimate
the
expected
downtime per year for this system.
B.
Your system consists of 10 physical nodes connected with a redundant
network. The system is designed in such a way that 9 out of 10 nodes
must be running for it to provide service. Each node has a probability
of
failure of 1% in a given month, and it will take about 6h to fix a failure
(or replace a node). Estimate the
expected
downtime per year for this
system.

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so if i do it an infinite times the chance is 0?

>>8392847
That's the probability that it closes successfully on the first 99 tries and fails on the 100th.

Clearly, the chance of it closing successfully on all of the first N tries decreases as N increases.

>>8392864

im a fugging brainlet fugg :D

you have to program a robot to survive as long as possible by keeping it on a platform without falling off. the robot starts in the center and he must continuously make steps left or right. you get to give the robot a list of commands that determines the direction of the steps, e.g. L,R,L,R,R,L,R,L,L...

however, the robot may choose to skip every N commands, such as L,_,R,_,R or R,_,_,R,_,_,R

what is the largest number of steps you can guarantee the robot will survive with a platform of radius of C = 4 ?

>>8385880
I replied late. You're top notch. Thanks so much for this man.

>>8392909

this is genuinely interesting, i am no /math/ but let me try.

The sequence cannot be arbitrary, because for an arbitrary sequence G and assuming its infinitely long, you can always find N where G_N = {L,L,L,L.....} or {R,R,R,R,....} the tail after 3 R's don't matter but it's enough that the first four is repeating.

So it must be algorithmic. But it also cannot be constant, like G = {L,R,R,L,R,R,L...} repeating forever because N = 2 will immediately fail. So it must be exponential or some sort, like G = {L,R,L,R,R,L,R,R,R,L....} but this is thinking that we can only remove R. If we can remove L, the sequence fails. So BOTH must be exponential, like G = {R,L,R,R,L,L,R,R,R,L,L,L,R,....}

So I bet the answer is 4 steps still lmao.

>>8392919

Sorry, I meant linearly increase in sequence. But I guess exponentially would also work

>>8392909

n(n + 1)/2, where n = C.

>>8392934
What about: Your system consists of 10 physical nodes connected with a redundant
network. The system is designed in such a way that 9 out of 10 nodes
must be running for it to provide service. Each node has a probability
of failure of 1% in a given month, and it will take about 6h to fix a
failure (or replace a node).
Estimate the expected downtime per year for this system.

>>8392941

what the fuck does this hav anything to do with the robot? are you homework-fagging

>>8392919
L,R,L,R,L is a sequence in which the robot survives 5 steps, the answer is a bit higher

skipping steps still counts towards the total, sorry if that was unclear

>>8392934

'no'

>>8392957

If that's the case then this is highly dependant on the value of N, take G := the set of ALL possible sequence and all of these sequences are infinitely long. Then there exist some N where there will always exist a sub-sequence of G where after N elements the element will repeat for 4 times.

G_n = {.......RRRR....}

>>8392962
that is correct but doesn't answer the question of what is the largest sequence that the robot must survive

>>8392968

I cannot guarantee any particular number but N.

>>8392909
wasn't there a singingbana video about this

>>8392989
yes you can, e.g. L,R,L,R,L is a sequence that guarantees the robot survives 5 steps

N isn't decided by you, the robot chooses how many steps are skipped

>>8392997

no it doesn't guarantee the robot survives 5 steps, because if N = 1 you are fucked, you aren't GUARANTEEing anyone anything, whatever sequence that you put the robot can always find some N that will fuck your sequence. so all i can say is that the robot will survive for N steps.

yes I don't decide what N is, and that is the crux of problem. It makes it impossible for me to guarantee anything.

>>8393004
if N = 1 the robot will not skip any steps. therefor, the robot following the sequence L,R,L,R,L will move Left, then Right, then Left, then Right, then Left without falling off of the platform

>"MATLAB has functions to calculate natural log, base-10 log and base-2 log, however, logarithms for any other base will need to be computed; there is no general logarithm function that allows the user to input the base."

WHYYYYYYYYYYYYYYYYYYYYYY?!

>>8393012
because it's trivial

>>8393010
correction, N = 1 is 1 skip so he will move Left, skip Right, move Left, skip Right, move Left and be 3 steps to the left and still inside the platform, not skipping any is N = 0

>>8393010

okay but can you first properly define the relation?

so if I have LRLRLRLRLR, what number should N be so that it will take L_L_L_L...

what's jojoba oil physics properties?

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Why is the bump limit 310 and not 300?

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>>8393546
You mean why is the bump limit 310 and not 314?

>>8393546

Shrekel invested in 4chan brah havent you heard?

>>8393552
Yes, that came to mind as well

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This is a question that google could not answer properly.

Regarding a discussion about global warming, someone mentioned that the temperature has increased since the industrial revolution more rapidly than ever (let's say some several of thousands of years). I was looking at the charts (pic related) and I have the following questions: what is the accuracy of the geological methods for measurement of the earth temperature?

Four important agency cannot agree with today's measurement (they agree on what's going on, but not on the precise amount.) If with today's tool there are difference in measurement+error, what is the error when measuring the temperature of the earth +1000 years ago?, as low as 0.1°C - 1°C?, or as high as +10°C?

Also, could it be possible that we are comparing different data like temperature close to the sea vs temperature of the at 1000 masl?

I couldn't find that on google.

>>8393012
Just use the change of bases theorem, pham.

Hey what is a determinant? I've read Lightstone's Linear Algebra and I don't remember him explaining exactly why a determinant of a matrix 2x2 matrix = ad - bc, like why not ac - bd??

I think he used induction like, given a matrix M;

if M_(1,1), then |M| = m_1,1

else if M_(n,n), then |M| = some row, then the matrix of that row, you know the deal

but he never explained WHY ad-bc, like why do we take the a row or a column than ignore them then take the determinant. It seems to me that mathematician define ad-bc as a matrix without a particular reason why other than it is somehow useful.

New thread
>>8394032