Stupid Question Thread /sqt/

was thinking why is the bond strength between H2 higher than that between F2?

How long would it take to complete the following:

Algebra and Trigonometry - Judith Beecher

Elementary Calculus - Keisler

Matrices and Linear Algebra" by Schneider and Barker

This group is spreading false information regarding cancer causing people to refuse proven tx in lieu of buying into their narrative. Please help expose them. Idk how to do this but I have read enough about 4chan to know there are intelligent people here who can make a difference.

https://go2.thetruthaboutcancer.com/agq-encore/qa-1/?utm_campaign=agq&utm_medium=email&utm_source=maropost&utm_content=2017-05-27-0800&utm_term=

>>8938061
prove the palindrome language over {0,1} is not in DCFL without using the pumping lemme for DCFL

My best attempt so far looks at the grammar and basically says it's impossible to find a deterministic context free grammar that creates the palindrome language.

I was revisiting high school physics and a book said a current produces a magnetic field. If that's so, then will leaving a small coin next to the wire make it attracted? If not why?

And why does cutting a magnet in half create two other magnets?

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I was looking through the yeast that settle at the bottom of the jug while making beer and i keep seeing these square looking things,
any idea what these are?

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>>8938558
The reason here is that there are less electrons in hydrogen and they repel each other lesser than flourine would do.

>>8938635
The magnetic field strength in a current carrying conductor is related by F = BIL, where F is the normal force experienced, B is the magnetic field strength and L is the length of the conductor. The magnetic field strength is actually very small. (Earth has about 50 microtesla. The MRI scanner reaching about 3 tesla.) This results a small force that cannot do work against the resistive forces present.

>>8938635
Magnets actually have "domains" or simply region of space where the area has same direction of magnetic strength. (Pic by earlier post) Cutting it into half will simply cause a new resultant magnetic field being created by the domains.

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WHAT THE FUCK IS "FIRST 9 WHOLE NUMBERS FROM THE RANGE OF VALUES"?!

IT DEPENDS ON FUCKING X.

WHAT THE FUCK?! PLEASE TELL ME FFS.


The median of this bullshit should be zero. Which IT FUCKING ISN'T HOWEVER YOU TRY IT FFS.

I need a method to study abstract proof based math

I'm going through my first class with it and the proofs on exams are killing me and it takes me forever to go through the homework

My professor says I present a lot of logical but not-quite-correct ideas in my work and office hours and that I simply must practice my proofs more

But how! There are no answers in the book and I rarely know if I'm 100% correct when I write something. How do you practice writing proofs effectively

>>8938754
>>8938761
So basically a domain is like the lego bricks that make up a magnet, right? Meaning if I split one Lego made of 20 blocks I just get two blocks made of 10 Legos instead. But what if I divide those as well to the point I end up with 20 blocks of one Lego each. And then hammer each individual Lego. I was thinking about that "quanta" thing, that energy is stored in packs that cannot be divided. So following the analogy does the magnetic field just stop existing altogether?

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Why is there a difference of voltage when resistors are in series, but not in parallel?

>>8938780
The closed form solution is [math]y = x^2 - x[/math], but your question makes no real sense. The range of the polynomial is -1 to infinity, so it could mean {-1, 0, 1, 2, 3, 4, 5, 6, 7}, the median of thse values being 3. The only other thing it could mean is if your function was a probability density function, which it isnt. So you're probably better off asking your teacher/lecturer/whoever what their vague ass question means instead of yelling at us.

How come there are so many foods that are perfectly okay for humans to eat but can be harmful or even fatal to dogs and cats even in small quantities?

Are there any foods that dogs and cats can eat that are fatal humans? Or do we don't know because we usually don't feed our pets things that kill us?

>>8938061
Why wouldn't this scenario break the law of conservation of energy?
>You have a gun that shoot a bullet at 100m/s
>You can run forward at 5m/s
>You run at 5m/s and shoot the gun at the same direction you are running at
>The bullet goes 105m/s

Since [eqn]KE=1/2mv^2[/eqn], why does the kinetic energy that takes to run at 5m/s from 0m/s, also make something go from 100m/s to 105m/s when there is a squared relationship on velocity?

>>8939044
someone please answer this

>>8938754
>The reason here is that there are less electrons in hydrogen and they repel each other lesser than flourine would do.
thanks bb

>>8938875

voltage across what?

If the average time is 16 seconds for a car to travel 5km how do I find the average speed

>>8939044
the you-bullet system has a total kinetic energy of K. It also has some chemical energy stored in the gunpowder. When you fire the bullet, expanding gases do more work on the bullet than they do on you (work done on you is negative, because the force opposes system's motion), thus increasing the system's total kinetic energy.
Momentum, however, is conserved, since no outside forces are at work (gases push the bullet forward with equal force that they are pushing you back with)

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>>8939163
Here's an example. A circuit with two resistors in series. If you plug a voltmeter to (1) and (2), and then to (1) and (3), you'll see there is a difference in the voltage measured. Hence if you sum all voltages it will be equals to the overall voltage. So the question is how exactly does this work and why is it happening.

>>8939269

there will be zero volts between 1 and 2.

Point 1 and point 2 are the same point. There is 0 ohms between them since in a schematic, a wire has no resistance. That means that they will have no difference in electrical potential.

if both the resistors are the same, there will be .5v+ across 1 and 3, and then .5v+ across 3 and the positive terminal.

>>8939167

distance divided by time

Can somebody explain in an intuitive way why multiplication by the Jacobian matrix results in a transformation of coordinates?

I see how it works in practice -- like for example transforming rectangular coordinates to polar coordinates and vice versa -- but to me it's just "magic" that multiplication by the Jacobian matrix accomplishes this transformation.

Is there some bit of insight that will show me why the Jacobian does this?

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>>8939302
Thanks.
>if both the resistors are the same, there will be .5v+ across 1 and 3, and then .5v+ across 3 and the positive terminal.
That's assuming this is a 1.5V battery right?
Look at this example now. Can you help me? To me it makes more sense now, btween 1 and 2 in >>8939269 there's zero voltage. But now look at this picture I made, with improved graphics. How would I calculate the amperage and the voltage in different points of these two circuits? And why is there a difference in voltage when you measure stuff between two resistors?
PS I hope it doesn't come out as I'm some highschool kid, I'm an adult.

>>8939309
Also another thing I don't understand is why must there be always a ground attached to circuits? I'm using a "circuit simulator" app to experiment and relearn these things, but my circuits never work if a ground part is connected to the circuit. Why??

>>8939309

The voltage of the battery would not matter if you built that original circuit. It would be half of whatever the voltage is across each resistor.

No matter what resistance you have, the negative terminal will always be 0v and the positive terminal will always be whatever voltage the battery is.

So divide 1 by the sum of all the resistors' values. What you have is the voltage drop of one ohm. Start at the positive terminal. multiply it by each resistor to get the voltage drop. across that resistor.

To find the current, find the total resistance. For resistors in series, it is the sum of the values. Then you solve the equation v = current*resistance given the voltage of the battery and the total resistance. This does not change at any point in the circuit.

>>8939316

The ground is necessary because there has to be a difference. Otherwise, there is no reason for the energy to leave the battery.

remember: the minus terminal of a battery = 0v = ground

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>>8939371
I kind of understand it better now. I think so. Let me see if I got it right. In the example at >>8939269, the "voltage drop" would be 0.5 and 0.5 if resistors were the same size. So in the left example at >>8939309, the first voltage drop (5 ohms) would be 4 times the size of the second voltage drop (20 ohms) (5:20 = 1:4), in such a way the sum would be equal to 100? So we would have 20 and 80?

And if the two last lines you wrote are true, then why do batteries work the way they do? I mean, let's say... I'm an astronaut, and I'm floating in space. If I hold a phone in space, the phone would still work if the battery is charged, right? It's not connected to any ground, it's in fucking space. So what exactly is this ground? I understand an earth wire or whatever the technical name gives a kind of infinite sink for electrons because it's so massive compared to the circuit. So how come things with batteries supposedly work without being attached to earth or comparable body?

>>8939393

"Mains earth" AKA "earth" is the wire that is connected to the dirt.

Some people in the US call what is really earth "ground", but that's just retarded.

You would use earth when you want to prevent something from becoming charged and shocking you. That's another topic.

Battery minus = 0v = ground =/= mains earth.

A real life battery that would work in space or on Earth is made by taking one chemical that has too much electrons, another chemical that wants more electrons, and then insulating them from each other. One chemical is - the other is +.

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>>8939417
Thanks. I think that answers most my questions.

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Actually here's another question on electricity. I was reading and it seems electrons in a circuit travel anywhere between 50% to 99% of the speed of light. Aren't those relativistic enough to, for the lack of a better term, fuck up spacetime? If yes, what exactly are the practical effects of a circuit with a current flowing in relativistic speeds? Do electrons in relativistic speeds have anything to do with magnetism?

>>8938061

Are there any scientific things that are shaped like the pseudo-scientific Kabbalistic Tree of Life? Mathematical graphs, molecules, etc.

>>8939591
have you ever had a physics 2 or higher class yet? or are you just spouting buzzwords you found online?

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>>8938875
Drew a picture showing a circuit in the form of the water analogy that is commonly used where it is thought of as water flowing through pipes and resistors are pipes with smaller diameter, etc... I labelled voltages of each resistor to show how a circuit may work with resistors in parallel vs series. In parallel, the two resistors pipe water from the same starting pipe to the same end pipe so the voltage (potential difference) will be the same as they are the same initial and final pipe. In series, the voltage of the 1st resistor will be the potential difference between the initial pipe and the water just after the resistor. The voltage of the 2nd resistor will be the potential difference between just after the first resistor and the final pipe. Of course this value adds up to 5V still because they are the same initial and final pipes.

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>>8939712
Why doesn't the electron just take the shortest path? For example, in this image, why doesn't the current flow only through 8721? If the current exists because of the negative side repelling electrons and the positive one attracting them, why wont electrons just follow the shortest path? Let alone be spread evenly across the paralel circuit when resistors are equal? Also why is the speed the same in all parts? Why don't electrons go faster when they are close to the battery than they are when they are away, if Coulomb's law has distance be one of its factors?
>>8939674
No, I'm a 20 something yo highschool dropout studying highschool things. I don't know the correct terms. All I was pointing out is the electrons move in speeds very close to the speed of light according to all sources. And I know crazy things happen when you approach the speed of light. Like time dilation and lengthy contraction. The effect increases exponentially around 80% of c. So I asked what that means for a circuit. What happens when you have a circuit with amperage at 99% the speed of light. From an electrical point of view that is. I also know circuits have something to do with magnets so I'm wondering too what's the connection between relativity, speed of light, electricity and magnets. Yes you may say for now I'm just spouting buzzwords I found online but this is like my third day of physics. How much time of study did it take you to learn the things I did in three days? Including so far transistors, capacitors, even logic gates, relativity, superposition, tunnelling etc. For now its all just theory but I'm excited to jump into the math.

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>>8939775
Wrong image. Sorry. use this one for reference.

Is there a way to algebraically find the solution set of x of f(x) = 1 if the solution set would be something like (0,2),(4,5),(9,10)

>>8939591
>I was reading and it seems electrons in a circuit travel anywhere between 50% to 99% of the speed of light.

No, electric fields move between 50% to 99% the speed of light but electrons don't. They drift along with the current at only 1.38mm/minute (for comparison sperm moves at 4mm/min) and they move around randomly at around 1570km/s (less than 1% of the speed of light).

>Do electrons in relativistic speeds have anything to do with magnetism?

Magnetism is a relativistic effect.

>>8939778
You have current on all 3 paths, just on different levels. According to Ohm's law, there will be more current on the wire according to its resistance, so we can say Ir3>Ir2>Ir1. But then, back to your question, why doesn't current just flow through R1? R1 and R2 are more conductive than R3, this way it's easier for electrons to partially flow through all 3 wires, in inversely proportional amounts to each wire's resistance. So, again, Ir1>Ir2>Ir3

>>8938998
>The closed form solution is [math]y = x^2 - x[/math],
pls expand

>>8939775
>>8939778
electrons will always try to minimize a potential difference if one is present (the battery). in circuits and parallel resistors the potential difference manifests itself across all the resistors. since there's a potential difference across the resistors the electrons will want to move through it. if the resistances are all relatively the same the electrons will go through the resistors at relatively the same rate [math] I=\frac{V}{R} [/math] (ohm's law). if one resistance is significantly lower than the others than you observer a "short circuit" where most of the electrons will go down the lower resistance path. but physically there will always be electrons going down each path because there's always a current if there's a finite [math] R [/math] in [eqn] I=\frac{V}{R} [/eqn].

so to sum it up, battery manifests potential difference across each resistor. electron wants to minimize it. electron moves through all of them because potential is across each one

How the fuck do I learn complex analysis in one day?

>>8940053
>How the fuck do I learn complex analysis in one day?
Go to the North Pole and study there

Could you walk on the outside of a Dyson sphere? How hot would it be? Could it have an atmosphere? If there was a missing panel how close could you get to the hole? What would happen to the atmosphere? What's stopping the sphere from getting misaligned and crashing into the sun? What would happen? Other than a fucked up sphere, obviously.

Can anyone here explain the difference between these formulas (the standard errors)

https://i.imgur.com/CJNljub.png

>>8939302
so 5/16? This gives 0.3125 and doesn't really seem right for an average speed of something

>>8938797

Someone pls help

>>8939307
consider the geometric implications of a matrixdeterminant in general

>>8940282
>>8939307
also this addresses your question well but it's in czech https://math.feld.cvut.cz/tiser/iweb3.pdf

[math]\int_{0}^{+\infty} \frac{1}{(1+t)^{2}(1+t^2)}[/math]

is it possible ?

>>8938780

HOW DO I KNOW THE RANGE OF VALUES OF THIS FUCKING THING FFS?!

>>8940383
>is it possible ?
Pi/4

>>8940394
how?

please I'm struggling for a long time

>>8939993
[math]\int_{0}^{x} (k + 1) dk = [\frac{1}{2} k^2 + k]_{0}^{x} = \frac{1}{2} x^2 + x[/math]
Understand? Now stop fucking crying, it makes people not want to answer your question

>>8940398
>how?
>please I'm struggling for a long time
[math]\frac{1}{(1+t^2)^2}=\frac{1+t^2-t^2}{(1+t^2)^2}=\frac{1}{1+t^2}+\frac{t^2}{(1+t^2)^2[/math]
The first one gives you an ArcTan and the second one gives you t/(1+t^2), with appropriate coefficients.

>>8940398
As with most integrals, substitute t = tan(x), after that its ez ez

>>8940406
>[math]\frac{1}{(1+t^2)^2} = \frac{1+t^2-t^2}{(1+t^2)^2} = \frac{1}{1+t^2}+ \frac{t^2}{(1+t^2)^2}[/math]

[math]\frac{1}{(1+t^2)^2}[/math]

how to get this?

>>8940408
what to do after?

sorry for being a brainlet just need more details

>>8940399
Well that's what I fucking get and it makes no fucking sense so

>>8940412
Well for one, >>8940394 this guy got it wrong, the answer is 1/2. For two, tan substitution might not be the best way to go, although it looked a good pick as it makes 2 terms immediately cancel, it still works though but its a pain.
What I would now reccomend is substituting t = 1/x and doing some tricky shit that I just did, i'll give you a write up in a second

>>8940412
Oh It's ok I found it :

[math]t = tan(x)[/math]

[math]\int_{0}^{+\infty} \frac{1}{(1+tanx)^{2}(1+tanx^2)} (1+tanx^2) dx[/math] = [math]\int_{0}^{+\infty} \frac{1}{(1+tanx)}^{2}[/math] = [math]Arctg(+\infty)[/math] = [math]\frac {pi}{2}[/math]

I hope this is right, thanks guys

>>8940435
oh... so >>8940437 isn't right?

>>8940438
I'm afraid not, you got the last integral wrong, arctan(x) does not equal that, and you didn't substitute the limits correctly.

>>8940440
oh yeah I didn't see it clearly, I'm very lost

could you type the steps please?

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>>8940443
Too much to type out so I wrote it, I have the handwriting of a 3 year old and sometimes skip steps, sorry
Its a difficult integral and this is a fairly abstract way to do them, typically when you do an integral like this where you need to preserve the limits to be able to manipulate it you'll do t = 1/x for 0 to infinity, and t = 1 - x for 0 to 1, if that makes any sense

I have a sine graph that shows the depth of water over time. I need a formula that I can use to find for how many hours the depth is above a certain height.

>>8938061
Any good books on Computer Vision?

How do I create a rubik's cube animation like this from scratch?

https://www.youtube.com/watch?v=xlwORzo2OJ8

t. brainlet who likes Image Processing

Do definite integrals find the area for the inclusive or exclusive domains?
\int_{a}^{b}f(x)dx finding the area for x \in (a, b) or x \in [a, b].

The area should equal the same value, just wondering if this is a question that should be asked.

>>8940450
Wow this is brain melting

but can we write : (1+1/x)^2 = 1/x^4(1+x)^2 ??

I had to precise that the question of this equation says :

Solve ( if possible ) [equation]

ive asked this question countless times with no replies but: does anyone know if 2 summer REUs would be enough research experience to get into a top 20 EE phd program? Im looking to get into umich or uiuc if thay matters.

>>8940467
No, but you can write (1+1/x)^2 = 1/x^2(1+x)^2
[math](1+\frac{1}{x})^2 = ((\frac{1}{x})(1+x))^2 = \frac{1}{x^2} (1+x)^2[/math]
I also took a factor of 1/x^2 out of the (1+1/x^2) term

>>8940474
dude thanks a lot, but If I got this in the exam I'm not sure I would be able to do it

>>8940479
Its a pretty horrific integral, but if you wanted questions that need you to do stuff like that, check out the integral questions on some STEP papers, thats where I learnt it

>>8940499
I just realized my shit level in maths, even though I'm physicist, I will try to catch up this summer and I hope I pass this semester.

what you do to help improve your level ?

>>8940506
The only way to get better at integrals is a lot of practice doing integrals, first it will build up your intuition of when to do different techniques, then it will build up your mental vault of patterns so you can just recognize some integrals from the sight of them. There isn't really a shortcut.
This is assuming you already know the techniques; substitution, integration by parts, partial fractions, etc.

>>8940511
yeah, I know all the tricks, but don't have that quick wit to tell what should we do at first glance

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Can someone help a brainlet like me understand spatial autocorellation?

What I'm having trouble understanding here is the term w. I understand its the weight of some shit obtained with a weight matrix, but what is it conceptually speaking? Is it a decimal that is meant to lower the degree of correlation if the variables are not well clustered?

>>8938558
The weak force is a Jewish Meme designed to keep you unaware of Quarkstein's Number.

>>8939029
Dog shit cleans the skin off leather. It's that simple.

>>8939029
Because we are bigger, and have evolved to be omnivores. However, cats and dogs being carnivores gives them a greater tolerance for things like raw meat than us.

>>8940282
>>8940290
> implications of a matrix determinant in general

Thanks. I already have a good intuitive understanding of how the determinant specifies how much the area scales when performing the matrix multiplication.

What I'm hung up on is trying to figure out why its the act of taking the *partial derivatives* that achieves the correct transformation.

I do understand how the Jacobian directly maps a tangent vector from the domain into the corresponding tangent vector in the range. That's because the tangent vector is determined by the derivatives -- and obviously the Jacobian is supplying those derivatives.

What I'm missing is that final bit of intuition about why the Jacobian also achieves the coordinate transformation for the actual function value itself (and not just the tangent vector).

Everything I read focuses heavily on the determinant, which I already understand. I guess I need something more basic, which is why the derivatives are taken in the first place, and how its geometric interpretation (i.e. the tangent vectors) leads to the transformation of coordinates.

>>8939591
I plugged a battery into my Akai TV remote and it destroyed spacetime. That was in March.

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could someone provide me a proof for pic
thanks

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>>8940290
We should all be IN CZECK!!

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>>8940599

>>8940629
thanks mate

>>8940596
It doesn't supply the value for the function itself, only the area thing. You use function composition for the function value.

can an element of a subset be a function? And can that function be used for mapping particular subsets?

like if f is an element of F, can I say for some arbitrary process f:O->R where

>>8940725
Am not sure if my question qualifies.

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>>8938061
Could someone give me a quick rundown of how pic related is deduced?

It is used as part of a proof for the prime number theorem but no comment is given about it. The author just pulls that inequality out of his ass and me never having worked with the logarithmic integral I do not know how that is deduced.

>>8940815
when t is between 2 and sqrt(x) you have
log2 <= log t

so
1/log t <= 1/log 2

so
integral of 1/log t from 2 to sqrt(x)
<= integral of 1/log 2 from 2 to sqrt(x)
= [sqrt(x)-2]/log 2
<= sqrt(x)/log 2

>>8940831
Ah, that's right. Pretty simple too. I thought it would be more complicated because it gives a really strong bound.

You see, what is being proved is that when you divide that integral on the left by x, and then take the limit to infinity then it gets to 0.

And when you take the inequality on the right and divide it by x, and take the limit to infinity it still gets to 0. So with that really inneficient approximation you still get the bound you need.

Thank you my man, I'll see if I can figure out the other part on my own.

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>>8940815
Hope my drawings good enough, he's effectively comparing the areas of the 2 boxes and the integral, he could make it stricter by removing the far left bit but he hasn't, no clue why

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i fucked up and made a new thread, anways

help a brainlet out

im supposed to use software such as matlab, sagemath etc to solve this exercise.
hope my translation is understandable

first im writing the function as this to use in software
c(x)=((pi)((300/cos(x))2)0.8)/((pi/2)(14)2(1+sin(x)-0.5*cos(x)))

is that right?

now

problem: considering h=300, F=0.8 and D=14, find the positive angle A inferior to pi/25 for which C=1200.

a)find a function f(x), for which the solution of f(x)=0, is equivalent to the solution of the problem.

i dont understand this question at all, also here's the original in portuguese: encontre uma função f(x), cuja solução de f(x)=0, seja equivalente à solução do problema questão.

b) make sure that in the interval [0,pi/25] you can use the secant method

im not sure here i think f has to be differentiable twice in the interval and that f'(x) cant have roots in the interval correct?
i dont have to worry about if f(0)*f(pi/25) is less than 0 right? because it isnt

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>>8940736
This was the question:

"Compute the equation of state of a Fermi gas where its chemical potential is negative. Use the relation between pressure and the grand canonical potential."

>>8938797
propositional logic, stanford or mit website
also the book "How to Prove It"

If I have a group of order p^n, how do I show all groups of order p^(n-1) are normal subgroups?

>>8938797
>Make friends with math majors/grad students/professors
>Have them check your proofs

Or LaTeX them up and post them here so we can relentlessly mock you.

>>8941029
>relentlessly mock you
this is a no bulli zone

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is there actually going to be an era of black holes where stars never form again, or is this just speculation based on what we know?

If lotion says on the bottle it will protect your skin for 24 hours, is that assuming that you do not wash your hands at all for those 24 hours? Or will it still convey some sort of benefit even after you washed it off?

>>8941207
It means nothing either way, don't believe whats on bottles of lotion.

>>8941216
Well of course I don't believe 100% of what they're saying, but the product has helped me before when my hands get so dry the skin starts breaking up into little cuts and that kind of thing, applying the stuff before bed for a few days usually clears it right up for a while.

>>8941221
It seems you have answered your own question, young one

Is p=np really a mathematical problem?

I am being retarded again. Let [math]\{ X_n \} [/math] be any martingale. How do I show from the definition that [math]X_n - X_{n-1}[/math] is independent of [math]\mathcal{F}_{n-1}[/math], where [math]\{ \mathcal{F}_n \} [/math] is the natural filtration?

>>8940469
one of you phd fuckers answer me now before i start a new thread pls

>>8940469
Why don't you post it on /adv/ where it belongs and can be answered, and not get your thread moved and yourself warned

>>8941234
Isn't that just because it's conditional expectation is zero (which doesn't depend on the filtration)

>>8941276
It is yeah. I'm trying to prove something, and in the proof I need to show that:

[eqn] \mathbf{E}[X_n - X_{n-1} | \mathcal{F}_{n-1} ] = \mathbf{E}[X_n - X_{n-1}] [/eqn]

>>8942226
funky F sub(n-1) = 1, my homie

>As a corollary, P=NP
>proof is left as an exercise

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i usually see the riemann hypothesis called the most famous unsolved problem in mathematics

was fermat's last theorem more famous before it was solved, or has riemann always been more famous?

>>8942246
A maths problem being famous is arbitrary and unmeasurable, so your question doesn't have an answer

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>>8942492
>bothering to post such a meaningless post
next?

>>8942246
Very hard to judge. Although Femat's is a lot simpler to explain, there wasn't the same proliferation of internet that we have nowadays so may not have been that well known outside of maths circles. On the other hand, it's actually surprising how few people who aren't involved in maths have even heard of the Riemann Hypothesis.

Can you melt hair into a homegenous mass without combusting it?

>>8942512
>the weeb asks a shit question
>he is then confused when he gets the only answer his shit question deserves
next?

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>>8942559
>>he is then confused when he gets the only answer his shit question deserves
what confusion? this other answer was far better than you'res anyway:
>>8942515

Fermat's did have several monetary prizes attached to it long before the Riemann hypothesis, and far more incremental progress, so it probably was more famous

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>>8942599
>you'res
incredible

What's a good book to start the study in FEM for a mechanical engineering student? There's nothing in the wiki.

anyone here have an optimal solution for 3 graph coloring?

>>8940859
Do you know what the secant method is? Use it, find the solution to A for the problem and use the line as an f(0)=solution.

>>8942552
Yea, you just need a good vacumm.

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Is this context free language or context sensitive language? I think that it can be recognized by pushdown automata.

>>8942748
ehh, you just need to learn the software packages. pirate solidworks and do the tutorials.

if you want to get into the nitty gritty of programming FEM algorithms then i'd suggest picking up a numerical methods text and a text on PDE's as a start.

>>8942776
Idk what you are talking about, but how could it not be context sensitive when you dont know what a and b are?

>>8942797
Is Solidworks the most used software package? I was looking for books and some came with ansys.

For the beginning, I want just to apply the problems, but I want to be able to eventually apply some algorithms to solve shape optimization problems, will the software do that for me?

>>8942776
I suspect you're wrong. Think about what the stack of the pushdown automata would have to look like after a^(x+2)b^y.

>>8942226
Well you know that
[eqn]\mathbf{E}[X_n - X_{n-1} | \mathcal{F}_{n-1} ] = 0[/eqn]

now take expectation of both sides

[eqn]\mathbf{E}[\mathbf{E}[X_n - X_{n-1} | \mathcal{F}_{n-1} ]] = 0[/eqn]

now the expectation of a conditional expectation is just the expectation, so the left side simplifies and

[eqn]\mathbf{E}[X_n - X_{n-1} ] = 0[/eqn]

>>8942847
Damn why didn't I think of that? Thanks mate.

>>8942859
you're welcome. Doing it with equations like that feels non-intuitive to me, even though looking at the proof it looks really trivial, and I guess it is.

I think of it as "F_{n-1} gives us no information about X_n - X_{n-1} , and therefore doesn't affect its expectation when we condition on it"

>>8942246
>was fermat's last theorem more famous before it was solved
I'd say yes, by far.

>>8942865
>I think of it as "F_{n-1} gives us no information about X_n - X_{n-1} , and therefore doesn't affect its expectation when we condition on it"

Yes this is what I was thinking, but I couldn't rigorously prove it, now I can.

>>8938875
Because resistors resist voltage, not current.
When they're connected to the same node they share the same voltage.

What is Optimization as a field of study? Is it the same as Optimization in Calc I? How does it get more difficult other than (I assume) optimizing multivariable functions?

how do i represent the domain of quantification as a part of a countermodel created through a semantic tableau?
[math]I = \langle D, W, R, v \rangle[/math]
how do i represent [math]D = \{ ?? \}[/math]
including somehow the new existence predicate as well
i cant find a fucking example and my homework is asking me to give a countermodel formally

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1. Draw all of the non-isomorphic trees with 6 verticies.

2. In a full binary tree, find the expected value of the number of edges from a randomly chosen vertex to the nearest leaf.

3. For a connected graph G, prove that an edge e is in every possible spanning tree of G iff removing e disconnects G.

>>8942914
In my experience it's a bit vague. "Optimization" shouldn't really be considered a proper subfield of math. It's too general and the techniques you use depend on what you're optimizing and what the constraints are.

One hard example of optimization is integer programming. You can't directly apply any calculus techniques because everything is discrete.

But I guess you could sort of say that a lot of what people call "optimization" is just a glorified version of the problems you see in calc 3, but you're doing it in a lot of dimensions and your constraints are given by complicated inequalities.

I took a really shitty course in discrete math at my uni, and despite getting an A, I still don't know very much about discrete math but now I'm looking for resources to learn more. Any book reccomendations for the subject?

>>8942840
Yes, I was wrong. Now i get it. If there was something like x=2y, then it could be solved.

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I need a PDF defined and normalized on [0,1] that has the general shape of pic related, meaning large towards the edges and small in the middle.
Anyone know of one?

>>8943186
To add, I realize I can just pick something like (x-1/2)^4 and normalize it but it's more fun if something else with a fancy name already exists.

How good are my chances in the computer world without collegue?
Im talking about getting a job, one where i can develop actual things like idk google.

>>8943202
What's your major?

why is energy pressure times volume?

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I need to find if the series converges or diverges,but i don't know how to work asimptotically with it( i have a problem with the factor with arctan).
Below the factor is the solution the professor gave for that factor.
Could somebody please tell me how we get there?

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the purpose of this circuit is to detect changes in luminosity with the photoresistor. can someone explain to me like i'm a mentally retarded 5 year old why this needs the 10k ohm resistor followed by the ground connection? i really don't get it

>>8943306
from a dimensional perspective:

pressure is force per area
area is length squared
volume is length cubed
multiply pressure by volume and you are left with force times length, which is energy

>>8943306
Imagine a piston and a cylinder with cross sectional area A and height H. Then the pressure exerts force F to the piston by the pressure P such that F=P*A. The cylider can do work W with the length H with force F such that W=F*H. But F=P*A and A*H=V, where V is the volume of that cylinder so W=P*V.

>>8943350
my best guess is it's either to set up a voltage divider, or to prevent a short, don't know what that 210 or whatever connection is though

>>8938061
help with my math homework please. explain to me like i am a dummy, i am.

3x+5=-9x+7

solve for x

>>8943455
that's just the digital pin names for the arduino, 0 or 1 are for computer communication and 2 is the first free digital i/o pin

>>8943458
1/6

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How close/how many earthlike planets can be in the habitable zone of a solar system together while still having stable orbits and shit?

>>8943472
please break it down for me

>>8943475
get x to be on 1 side of the equation and everything else on the other.

How do you prove 1+1=2?

>>8943478
and i do that by adding +-3 to both sides?

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>>8943480

>>8943350
>>8943463
looks like you would want to put the 0 pin between the photoresistor and resistor then, assuming you're making some sort of measurement with it that would set up a voltage divider

>>8943312
https://www.wolframalpha.com/input/?i=arctan+taylor+series

When n is very large 1/n goes to zero so you're interested in the expansion around zero. As you can see the first nonvanishing order is 1/3n^3

>>8943480
Just consider it an axiom

>>8943697
<code>
y = y
log (y) = log (y)
log (1) = 0, therefore:
log (y) + log (1) = log(y)
y + 1 = y
</code>

why cant I do this?

>>8943480
From the definition of +.

If + is defined in terms of decimal numerals, then 1+1=2 is effectively an axiom.

Using Church numerals, + is normally defined thus:
(1) x+0=x
(2) x+S(y)=S(x+y)

So:
S(0)+S(0)
=S(S(0)+0) (2, x=S(0), y=0)
=S(S(0)) (1,x=S(0))

>>8943517
that actually makes perfect sense

>>8943703
Because log(1) is 0

>>8943728
exactly, log(1) = 0

so..
log(y) = log(y) = log(y) + log(1)

>>8943703
Not a mathemagician but I think the definition of log might somehow be dependent upon the fact that 1+1=2. Essentially it'd be a circular argument

>>8943741
If log(x)=log(y) + log(z) that doesn't mean x=y+z. It means x=yz
>cs students

>>8943753
I thought log was a unit of measurement, like bushel or grain

>>8942927
BUMP, I only #2 at this point. Or perhaps just a pointer?

Do gas giant planets have a solid core under their atmosphere or are they literally just floating balls made entirely of gas in space?

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What if every time we go to sleep, we die forever, and wake up as a technically different person, except with the same memories, brain and body?
Is there even a way to tell?

>>8943891
>Is there even a way to tell?
Kill oneself so then the experience can be compared

Can someone help me w/ bottle rocket physics? I know the initial energy in it because E = PV and the forces acting on it would be the force of thrust, air drag, and gravity. Is there anyway I could at least approximate this? Thanks.

>>8943937
http://www.real-world-physics-problems.com/water-rocket-physics.html

is something like this what im looking for?

>>8943891
The fact that our consciousness is paired to a single brain would suggest otherwise. When you wake up, or at least for me, my consciousness is still controlling this body, or at least I have the memories of it. Now it's not like you can make this argument for people other than yourself, but why are "you" controlling your body+brain and not anyone else's instead? Whether this is proof of a soul in the traditional sense is doubtful, but it does suggest there's something that gives consciousness some significance. But this could equally be proof that my body (or whoever is thinking about this) is the sole most important thing in the universe because it has a consciousness/soul thing controlling it, because there is no way to prove the existence of a consciousness aside from one's own.

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How do I prove this? It's coin toss statistics, by the way.

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>>8944038
I think something is messed up in your picture because you have a (-1)! in your sum. I imagine you're trying to calculate the expectation of the binomial distribution? If so the related pic should help.

>>8944054
I'll be able to look at it later, but that looks like what I'm looking for, thanks. Haven't learnt how to handle factorials and sums algebraically, which is probably something I should look to learn. Know what sort of paper I'd have to take?

>>8944085
Probably look at a discrete math book? Most intro probability/stat books have a section on this sort of thing. There are few simple things you can keep in mind.

With factorials, the big thing to keep in mind is remember the definition, n!= (1)(2)(3)...(n-1)(n). With this lots of other formulas can be simply derived. For example, it's easy to see n!/n = (n-1)!.

With sums, any properties you have with additions will work with sum, with a few other extra tricks. For for instance, you have a more advanced version of the distributive property:
[math] \sum a \cdot x_n = a \cdot \sum x_n. [/math]
Another trick is switching the order of summation:
[math] \sum_i \sum_j x_{i,j} = \sum_j \sum_i x_{ij} [/math]
(this is valid with finite sums, and infinite sums of non-negative terms). The biggest and hardest thing to wrap your head around is reindexing:
[math] \sum_{i=m}^n x_i = \sum_{j = m+k}^{n_k} x_{i-k} [/math]
Often when sums are reindexed in board work or in a book, they just write it out. If you stare at it long enough, this will usually make sense. But if you're having trouble, you can always be more explicit, writing "let j = i+k", then replacing expressions with i in them with j in them using the above equality.

In general, take it slow, do your best to make sure everything makes sense as you learn it, and practice, and you'll figure it out.

>>8944137
Thanks.

To me two hours I spend on 4chan I feel like it's less time than 30 minutes of work.
Is this proof time is relative.
Does 4chan have a strong gravitational pull or what.

>>8943703
log laws
last step is not y + 1
it's the product

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Why is there a shadow below the fire?
I mean, if you have a candle in the dark, you'll see stuff, that means fire emits light.
If that's true, why is there shadow beneath the flame of the flamethrower here?

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Does complex analysis have something to do with Fourier analysis other than the coefficients?

>>8944318
It's blockin the sunlight which is way stronger. Imagine being lying down looking directly at the sun; you would be much relieved to have fire to protect your eyes from the sun.

>>8942945
Concrete Mathematics, by Knuth. It's very hard but very good.

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Every fucking time I use this equation its a few numbers off the answer. What the hell am I doing wrong? I watched a few videos on this equation and they all have whole number roots which any non retard can figure out without using the equation

>>8944344
>What the hell am I doing wrong?

Maths

>>8944344
Just practice more, and be more careful. Don't skip steps, write things out fully. Unless you're fundamentally misunderstanding something, it's just that you need to be more careful and patient.

>>8938676
some kind of crystals that don't dissolve in water or alcohol?
grit from some kind of grinding?

>>8944344
>not completing the square
With a little practice you can complete the square at least 3x faster. If you're allowed to, you could always just do it on you're graphing calculator, but that's not a good way to learn if you're not going to be able to do that in an exam.

brainlets im working with keep asking me to send them my paper for a chem class, i dont want them to piggy back off my hard work when they are too lazy to do it themselves. am i a cunt for not sending it to them?

>>8944409
No, unless they've come to expect this from you. If they're only friends with you for this purpose then they're full of shit. You should give them a recipe for particularly tasty bleach instead.

>>8943634
Didn't think about Taylor,i get it now,thanks.

Which operation has two numbers on top of each other surrounded by brackets?

>>8944590
>Which operation has two numbers on top of each other surrounded by brackets?
Binomial coefficient.

>>8944593
Fuck that's it.
Thanks a lot anon.

>>8944409
change things in the discussion and conclusion

send them a faulty version

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>>8944629
beta as fuck, be alpha like your president.

>>8944655
lel

Say you have a double integral

[eqn]\int^U_L\int f(x) dx dx[/eqn]

i.e. an indefinite integral followed by a definite integral. However, the first indefinite integral [math]F(x)[/math]does not exist. Is there any way to approximate the answer to the overall double integral? I know you can approximate single integrals with Simpson's method etc, is there some way of extending this?

I have a test in 1.5 hours.

What can I do to activate my brain?

>>8938635
Yes technically... But it depends on whether or not the metal the coin is made of is para or diamagnetic

>>8944814
Try a bullet

Give me some suggestions on what to learn next.

Anything interesting/useful/fun, I just like knowing things, but I feel like my main source of information (youtube) has put me in a rut where I'm only watching tepid top 10 vids of varying subjects and not getting much out of it.

>>8944850
Learn some discipline and take a university course. If you're a poorfag, watch some of the myriad of lectures on youtube.

>>8944785
It makes no sense to approximate something that doesn't even exist. To which value should that approximation converge in your opinion?

>>8944862
I'm already in uni, but the semester is over and I want to learn something else for once.

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Why were Indian Mathematicians so ahead of European Mathematicians?

>90 exercises per section

Should I do them all, sci?

>just got BS in psych
>minor in math
>regret it
>want to get masters/phd in mathematics
is it at all possible?

>>8940456
Bump

>>8944421
>>8944629
>hey anon my parents both died in a double torture homocide so I didn't have time to do my homework, it would mean the absolute world to me if you, my friend, would lend me your homework this one ti-
Hahaha I knew it you were only my friend to piggy back off me, you're full of shit, drink bleach retard
*farts*

How can I think about the difference between

'For all x (P(x)->Q(X)) and "For all x P(x) -> For all x Q(X)


Does the first say that if x in the domain satisfies P(x) then x also satisfies Q(x) so theoretically there could be 1 x that is satisfied and the second one says that all x in the domain have to satisfy both P(x) and Q(x)?

>>8945543
What do you mean by ->, implies? Maps to?

>>8945547
Can you post this in >>>/adv/ where it belongs and can be answered?

>>8945552
-> is implies yeah

>>8945559
Then they mean exactly the same thing, the second for all is redundant, you're thinking about it too hard.

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ALGEBRREEEEEISTS help

>Show that a ring is a domain if and only if { 0 } is a prime ideal.

Very trivial, yes, however pic related is how our TA answered the question. What we have learned so far is that for a commutative ring with unity, the above proof would indeed be correct. Namely that R/I is an integral domain if I is a prime ideal. Not neccesarily for any ring. What am I missing?

Keep in mind we haven't learned about Prime Facorization Euclidean Hausdorff R^3883 domains yet.

>>8945552
They're called meme arrows.

>>8945610
Actually, no, I see that it says R is a domain in the TA's notes, not integral domain, that makes much more sense. I think I can prove that R ring => R/I is ideal if I is prime myself. Any additional insight would be appreciated, though. Looking at you, mr Langlands.

>>8945610
>>8945618
i can't even tell what you're stuck on but it's pretty straightforward

R is a domain <=> ab=0 implies a=0 or b=0 <=> (0) is prime

>>8945618
>mr Langlands
Who?

>>8945625
Obviously, just wondering why the TA used that R ring, P prime ideal => R/P is a domain without us having learned that. Does it follow trivially from something?

>>8944886
>It makes no sense to approximate something that doesn't even exist

The integral of a normal distribution ''''doesn't exist'''' in the sense that a function f(x) which fits the properties of the integral has not yet been discovered. But you can still calculate the definite integral of f(x) to an arbitrary degree of accuracy via numerical methods, which is just as well because we do this every single time the distribution so commonplace it's literally called the "standard normal distribution" is employed. If you don't know jack shit about the topic at hand, try shutting the fuck up before shooting your mouth off.

I failed Calc II last semester. Like, our professor is uploading lecture videos and the like online and they are free to watch. I attended the lectures and made notes.

I'm thinking about watching the lecture a second time but eventually it's a waste of time and the time could be used for practising. What's in your opinion the smarter way? Watching the lecture again or just work problems all the fucking time?

Just had ACL surgery and my dick is itchy, did they stick a catheter in and not tell me

>>8945666
work problems

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>>8945661
You should rather question your notion of "existence" before trying to compute integrals.

>>8945659
>P prime ideal => R/P is a domain
suppose (a + P)(b+P)=P. since (a+P)(b+P)=ab+P this implies ab is in P. since P is prime, a or b is in P, so a+P=P or b+P=P, so R/P is a domain

Say we have a function of displacement with respect to time.
[eqn]x(t) = t - \frac{t^3}{4}[/eqn]
on the interval [math]t \in [0,2][/math]
And we have the the Force [math]F[/math] with respect to time
[eqn]F(t) = -\frac{9t}{2}[/eqn]

What is the work if there is no displacement? Apparently zero is not the correct answer.
At [math]t_{1}=0[/math] [math]x_{i}=0[/math] and at [math]t_{2}=2[/math] [math]x_{f}=0[/math]
So the integral ends up looking like this [math]\int^{0}_{0}F(t)dx[/math]
Should the integral be split or something?

>>8945689
You should question your habit of nitpicking meaning instead of answering the question. This isn't a philosophy board. Of course, it's possible you're legitimately autistic and cannot parse everyday language, in which case you have my sympathy for being socially retarded.

>>8945802
You can use the alternate formula

Work done = F v dt

F = force, v = velocity

>>8945866
Yields the same result with the work being 0.
I guess the correct answer really is zero afterall.

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In a parabolic arc it possible to lose speed on your descent?

This kid in this manga grabbed a hunk of metal and launched himself into the air by riding said hunk of metal, using explosions to propel himself upwards

However, on his descent - that is to say AFTER the apex of his launch - he suddenly finds himself losing speed. That is to say, the hunk of metal he rides stalls, and he has to force it to the ground to win the race he's in.

Leaving aside the kid's physical well-being, Is there any scenario where a scenario like this could happen? Would the shape of the metal he's riding cause any significant drag to where he'd lose speed on his DESCENT?

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Worth leaving on a resume? Any big name uni helps in the filters right?

>>8940450
bait or just that dumb?

>>8945802
If your force acts on zero displacement, no work has been done.
Also, no idea what you're trying to do there with the integral. The polynomial [math] x(t) [/math] is not a straight line.

>>8945906
>blow moving ball in its opposite direction
>work done by the blowing force is zero when the ball slows down and returns to the position where you started blowing
are you sure? I read that the force is calculated from the total sum distance the force has been exerted on the object, not the displacement, to account for scenarios like this.

>>8945916
Not him, OP here
The question asked to specifically find the work done by the force by [math]t=2[/math]

Which is a roundabout way of asking for the net work done.

>>8945925
and net work done is always zero, making the answer zero

thanks

>>8938061
Does this graph look okay? Every Arrhenius plot I've seen has a negative slope with positive ln k values.

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>>8946006

>>8946006
>>8946011
Nevermind, I figured it out. I was using time instead of temperature.

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How to solve without lagrange multiplier?

>>8946084
By finding all local Extrema?
http://tutorial.math.lamar.edu/Classes/CalcIII/AbsoluteExtrema.aspx

>>8946084
>>8946084
I understand the equations of the circle must be [math] (x-0.5)^2 + (y-1)^2 = 0.5 [/math], with the equation of the other circle simply having y-0.5, x-1, but how do I compute the height of the endpoints using this knowledge?

Also, as a work check, I;ve found the critical point to be at y=x=3/4, and plugging this into Z resulted in 0. What I don't know how to do is check the endpoints, or if I even need to given the only critical point is x=y=3/4, and I know it to be 0.

>>8946094
see >>8946097
does that seem right? Perhaps I'm over-analyzing, it's been awhile

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I am about to kill myself over finding the particular equations of the non-homogenous parts in these relations.

I have literally no idea what to do. The homogenous parts are simple, but I'm about to burst a vein for being so stupid.

>>8946097
>>8946099
>>8946094
Oh, I forgot the second derivative test, but after that I'll know whether it's a maxima or minima, then would that answer suffice, anon?

>>8946104
I'm trailing comments all over the place but the second deritative test has revealed it's a saddle at (3/4, 3/4), so now I know that I'm lost.

>>8945802
>>8945906
>>8945925
Sorry to bother again but

I read that Wnet = ΔK
this would mean
[math]W = m*vf/2 - m*vf/2[/math]

I can get v(t) from the x(t) formula, and plugging in v(2) and v(0) into the above gives me W = 9/2 J

are you 100% sure it's 0 J?

>>8946084
If there would be a global optimum inside (in the open set!), its derivative would vanish - which is not the case here. So the optimum must be at the boundary. You could parametrize the boundary of the three simple sets that make up the domain (the two circles and the cube) and then find the optimum of these single variable functions.

>>8946117
How about you try to reverse solve the problem?
Find the points through the lagrange multiplier and then figure how to reach them through the extrema method

>>8946117
>3. The largest and smallest values found in the first two steps are the absolute minimum and the absolute maximum of the function.
Just plug in the points you found into the function and the largest value and lowest value should be your respective absolute maxima and minima

>>8946144
>mvf/2
What is this?
That's not kinetic energy is it?

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More of a request than a question. Can you recommend any good video series or reading material that can explain Mathematical concepts for dummies? I just finished my first year at University. I did quite well with my exams, but I don't feel I learned the fundamental concepts that much.

I'd like to understand the actual definitions and theory behind Mathematical concepts, but even looking through wikipedia is a fucking nightmare. Every second word is a whole new thing I know nothing about, and even if I've heard of it, I don't really know it in-depth.
Obviously I'm only a pretty basic level here. But for example, this past year I learned how to answer exam questions regarding complex numbers. I still have no fucking idea what a complex number is. I did well but I still feel like some Chink robot who just memorised the method and not the concept.

>>8946160
Don't know how to lowercase the f, no bully

meant [math](m*v^2)/2 - (m*v^2)/2[/math] where the first v is the final velocity and the 2nd v is the initial one.

>>8946165
Oh okay, and yeah I got the same value using your method.
Really weird.
Also, for making f lowercase just do this "_{f}"

>>8946170
Thanks. So I guess the work done is not zero after all? I'm really confused about this shit and I can't find a similar question in google.

>>8946157
It's a saddle though, so I assume it's max and min must be on the boundary.

>>8946153
We never went over the lagrange multiplier.

>>8946176
Well, following the questions that were asked beforehand the first thing that comes to mind when calculating the work would be to use [math]F(t)[/math] instead of finding it through [math]\Delta K[/math]

>>8946182
>We never went over the lagrange multiplier.
http://tutorial.math.lamar.edu/Classes/CalcIII/LagrangeMultipliers.aspx
Paul's Notes Online is your friend

>>8946163
3Blue1Brown if you can do at least calculus

>>8946183
can't see how it would make a difference in practice though

I fucking hate physics and their roundabout formulas, but thanks for the help

>>8946188
>I fucking hate physics and their roundabout formulas
Same

>>8946184
My issue is more one of time sensitivity, so I'm hoping to solve it using known methods or from a very kind anon (you)

>>8946188
Think of it this way, the object went forward and was then blown backward untill it reached the spot it launched from. In theory the net work should be zero because the force is constant and the distance is equal hence the difference in direction leads it to be zero.
However, when calculated through a path independent method, the work is 9/2. It could be that the work calculated through the path independent method belongs to the sum of the work done regardless of direction.
I guess that's one way to think about it, after all, physics is all about frame of reference.

>>8946194
I'm sorry man, but I can't help you any further since I haven't dealt with calc III in over a year.
My advice would be, try going for a third derivative?
Otherwise try what this>>8946145 anon said

>>8946100
See page 8 here: http://courses.ics.hawaii.edu/ReviewICS241/morea/counting/RecurrenceRelations2-QA.pdf

>>8946194
>>8946184
I'm starting to realize I might be able to solve it using a much more elementary method. I see that as y approaches 1.5, it contributes more positively to the height of the function.

I see that as x approaches 0 it negatively affects the height.

>>8946203
This sounds reasonable. Net work is zero while the other method is work done by distance not displacement, which also explains why 9/2 has a positive value (shouldn't it be negative as it pushes the ball back if that's not the case?). Thanks famalam.

>>8946145
Do I need to even check the cube? Wouldn't the cube be be checked by checking Z and by checking the two circles?

And unfortunately I don't know how I'd set up a proper parametrization for this.

>>8946084
bump, still desperately looking for answer

>>8946145
>>8946221
So, to explain why I don't get the parametrization, lets say I'm looking at the circle centered at (0.5,1). The equation for this is: [math] (x-0.5)^2 + (y-1)^2 = 0.5, and of course my function of Z is known. But how do I find the max height of Z at that outer half of the circle?

>>8946239
fucked up equation: [math] (x-0.5)^2 + (y-1)^2 = 0.5 [/math]

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>>8946185

exactly what I'm looking for. Have some reddit gold my #1 nigga

>>8946263
you can repay me by solving this >>8946084

>>8946210
Top notch, anon.
Clear up something for me though. I'm unsure on where s and t come from. From what I know, and it could be wrong, s is the degree of the coefficient to the left of the base, and t is the value of the base.

Am I at least close to being right?

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>mfw can't find a polynomial bijection [math] \mathbb{Q} \times \mathbb{Q} \to \mathbb{Q} [/math]

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>>8946239
For example, you insert the parameterization first (upper) circle [math] \varphi_1 (t) \in \mathbb{R}^2 [/math] into [math] z(x,y) [/math] and get the function [math] t \mapsto z(\varphi_1 (t)) [/math], defined on [0,[math] \pi [/math]] to [math] \mathbb{R} [/math].
Inside of (0,[math] \pi [/math]), you can apply the standard high school maths by computing the roots of the derivative. Then you also need to compare the values of z the boundary points t=0 and t=pi.

>>8945876
If he's already hit terminal velocity, then sure, the only thing you can do IS slow down. If his parabolic (it's actually elliptical on the scale of the Earth) arc has a horizontal speed close to terminal velocity, then as he gets into the thicker atmosphere he will be slowed down, regardless of the metal. The metal could also act as a small air brake if he's falling aerodynamically and changes his profile with the metal to give himself more drag.

>>8946084
In what universe would you not use Lagrange multipliers?

Fucking Laplace Transforms, man...

I have the following function I need to perform a Laplace Transform on pic related... The most I can come up with is the fact that there might be some sort of unit step function fuckery in it...

So far I have:
For the first one:
[math]
(1 - u(t-a))
[/math]
Second:
[math]
\frac{b-t}{b-a} \cdot (u(t-a) - u(t-b))
[/math]
and nothing for the third one

Can I just add the two functions together?

should you go to grad school near where your friends are

or even close by

friends are not grad school people

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>>8946542
Forgot the picture.

Have a sub 3.0 gpa in computer engineering from a decent public school. How to get an internship or related work experience this summer? Am I doomed? Yes, I'm a braiblet; at least not in debt.

>>8946305
https://mathoverflow.net/questions/21003/polynomial-bijection-from-mathbb-q-times-mathbb-q-to-mathbb-q
Please google before you ask us, and post it in the form of a question

>>8945802
Your upper bound of your integral should be 2, not 0.

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>>8938061
Pics the exercises from chapter III.6 in Mac Lanes Categories for the Working Mathematician.

my question is about question 1 and 2

>Describe the category ...
whats needed to describe a category? Do I just say what the objects and morphisms are?

>...Show that it has finite products.
im busy with this, but im now at 3 pages of work and im not done, and just want to make sure that im not missing something obvious that makes it a lot easier. my steps are
>Define the objects in the category of monoids in C
>Define the morphisms
>Construct a potential product and show its in the category
>Show the potential product satisfies the universal property by showing the morphism from any other object to it exists and is unique
>Construct a potential terminal object
>Show it satisfies the universal property
>Everything above is done using just the 3 diagrams used to define a monoid in a category + basic category axioms
It seems like im doing something wrong, and that this should be doable faster in another way.

relativistic length contraction is only real from the perspective of the non-moving frame right?

>>8947091
Correct, unless you're accelerating enough that the opposite side of your spaceship is going at a significantly different speed. I wouldn't count on that, though. Also dealing with accelerating frames is whacky.

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Is Newton's law of universal gravitation deprecated/obsolete?
Why?

I'm a student of psychology and unhappy with my course. I'm thinking about moving towards pure math because I have a love for geometry.

What can I expect from a pure math degree?

>>8947227
What a shit question, never post here again weeb

>>8947233
Math

>>8947227
no, its what you get when you let c -> infinity in general relativity, so when you can assume that its still fine and a lot easier to work with than GR.

>>8947261
wow, thanks. How haven't I figured it out?

>>8947274
One thing you can't expect from a maths degree is geometry, thats baby town

>>8946354
Ok, thanks anon. I'll try this later today. But why do I need a parametrization of t when I can solve the equation of a circle of x and y, respectively?

>>8947070
>whats needed to describe a category?
the objects, morphisms AND composition rule

>>8947404
>AND composition rule
thanks, completely forgot about that

My professor did a shitty job of explaining entropy.

I get the general idea of the universe becoming less ordered with time. What I don't get is what the measurements of it mean. How can we take such an abstract, qualitative concept as order and quantify it? When you do the calculations for the entropy associated with some kind of heat exchange, and you end up with an exact number of joules per kelvin... how does that number relate to reality?

>>8947264
You don't send to c to infinity, you make the metric a small perturbation of a flat metric and the stress tensor just an energy density.

>>8947426
yea, that too

>>8947420
heat is a form of entropy

>>8947364
You want the parameterization, because you can reduce the optimization problem to a problem with only one single variable. Then you don't need any Lagrange multipliers anymore.

A parameterization [math] \varphi : [0, 2 \pi) \to \mathbb{R}^2, t \mapsto \varphi_1(t):=(r \cos(t), r \sin(t)) [/math] of the circle with radius [math]r[/math] and center at zero, gives exactly all solutions [math]x,y \in \mathbb{R}^2[/math] with [math]x^2 + y^2 = r^2[/math], but for increasing [math]t[/math], you travel along the arc of the circle.
If you insert [math]\varphi[/math] into your function [math]z[/math], you only look at the [math]z[/math] values along that particular circle. And you want to find the maximum and minimum value of it.

And you just need to do it for the whole boundary of your heart-shaped domain, i.e. the two (half-) circles and the lines along both axes.

You'll probably also find plenty of videos about this by searching for "parameterization" and "optimization".

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When calculating the relative movement of this bar, is there a Coriolis component to take in consideration?

I feel pretty fucking stupid right now

lg x = 3,2

The book tells me x=1000, but it also tells me to do it like this x=10^3,2

what am i doing wrong?

>>8947443
That's deep brah.

>>8947466
Ok, I've always been uncomfortable with parametrization and optimization, so it only makes sense I can't see the solution. Thank you.

>>8947466
>>8947576
I will refer back to this once I have a chance to do some work

>>8947540
im guessing the ,2 means base 2 and lg = log_2, then just use the fact that log_b (x) = n means x = 10^n in base b.

>>8938061
An object is rotating with a tangential speed of 14 m/s, at a radius of 130 cm from the centre of rotation and the centripetal (radial) force is 39 N. Calculate the mass of the object.

>>8938061
Are every number equal to (sum of digits + product of digits) in a given base two digits long only ?
Thought about limiting like this :
b^(n - 1) <= N = Product digits + Sum digits <= (b - 1)*n + (b - 1)^(n)
Obviously the set is finit (when n -> +oo)
Wolframalpha couldn't give me solution.

Any idea ?

ie in base 10 : {0,19,29,39,49....,99}

in 2 similar triangles (where the corresponding pairs of sides all have equal ratios) is the ratio of a pair of sides equal to the ratio of the heights?

triangles ABC and DEF. a/d = b/e = c/f
but is a/d = h1/h2 where h1 is ABC's height and h2 is DEF's height?

>>8946914
You're finding the work, so the integral goes from the initial x (0) to the final x (also 0) and not time
It's literally the definition of work

>>8947803
Yes. I'm no geometer, but I'm pretty sure that all distances follow the same scale, the same way that all areas and all volumes do too. Run the cosine rule on it if you're unsure.

>>8948068
thanks man, i was just being stupid, when you resize the linear lengths of the triangle of course that includes the heights as well, the only fuckery happens when calculating the area, which doesn't increase linearly when you increase the lenghts of the sides linearly

Why is the Riemann Hypthesis called a hypothesis instead of a conjecture? Aren't mathy things called conjectures?

Maybe this is a bit of a Philosophical question, but is there another species that entertains itself in cultural ways? I mean, mental masturbation. Humans do things like music, architecture, art, dance, movies, plays and so on solely for entertainament and in my own terms what I call mental masturbation. Is there any other species that does something similar to this.

>>8948215
I mean, humans are obviously the only ones that make things like pyramids and complex videogames, but, say, do ants make small monuments out of dirt, or do chimpanzees play or wear banana leaves etc.

>>8946354
Can you help my retarded self one last time?

I've defined my x and y in terms of t, but don't know how to move forward with my single variable function of t. Is it as simple as taking the first derivative with respect to t and finding it's 0's?

>>8948328
Yes. And also check the boundary values of t.

>>8948342
I'm so skeptical it could be that easy. But I've already got soem solid guesses for what the abs max and min must be from some scratch work earlier, so if this works I owe you, math-anon. What's your background anyway?

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How accurate is this?

>>8948380
In principle it is completely true, but by how much time will dilate will depend on how close and how massive the black hole is. The difference could be just of a few minutes, or several decades.

>>8948215
Dolphins get high

What is the purpose of the Fourier integral? Just to introduce the transform? Seems a bit convoluted

>>8948405
Pretty sure it's for working out complicated waveforms that aren't simply a couple of sine waves.

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Yo niggas I don't know how this anon solved this exercise.

The last step is fucking destroying my brainlet brain.

I`ll be studying Computer Engineering next winter in spain, my question is what should I study this summer given that I didnt do any physics nor "hard" maths? pls halp