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/sci/ - Science & Math


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9656198 No.9656198 [Reply] [Original]

This thread is for questions that don't deserve their own thread.
>give context
>describe your thought process if you're stuck
>try wolframalpha.com and stackexchange.com
>How To Ask Questions The Smart Way http://www.catb.org/~esr/faqs/smart-questions.html

Previous thread >>9644659

>> No.9656200
File: 11 KB, 451x219, circularmotion.png [View same] [iqdb] [saucenao] [google]
9656200

My teacher gave me this formula for circular speed. I dont understand what the T stands for?

>> No.9656207

>>9656200
its the period

>> No.9656208

>>9656207
oh now i see, thank you

>> No.9656439

is there a scientific reason why i struggle with basic math but not advanced math?

>> No.9656468
File: 42 KB, 657x527, 1522023897813.jpg [View same] [iqdb] [saucenao] [google]
9656468

>>9656200
T stands for the period

>> No.9656478

>>9656200
The [math] T [/math] stands for period, its the time any given point on the circunference of the motion will take to return to its starting position.
[math] \omega [/math] is the angular velocity and since [math] v = \frac{t}{d} [/math] then [eqn] v = \fracc {\tau R}{T} [/eqn]

>> No.9656482

>>9656439
I have this problem too. Algebra was harder than calculus for me. It's probably because basic math isn't challenging enough to warrant effort.

>> No.9656540
File: 56 KB, 1107x800, c.png [View same] [iqdb] [saucenao] [google]
9656540

In convolution with f*g
why is the red g pictured backwards,
rising slope instead of descending slope?

source: https://en.wikipedia.org/wiki/Convolution

>> No.9656575

>>9656198
what's the inside things smaller than an atom?

>> No.9656628

>>9656575
probability waves

>> No.9656780

>>9656540
>In convolution with f*g
>why is the red g pictured backwards,
>rising slope instead of descending slope?
Look at the definition of convolution.

>> No.9656823

>>9656780
>definition of convolution
https://en.wikipedia.org/wiki/Convolution#Visual_explanation

well ok, why is the reflection in the definition?

>> No.9656836

>>9656823
If f is graphed on the k axis, f(h-k) is the same as flipping the graph over the vertical axis and then shifting right by h.

>> No.9657198

How do I prove that no matter the order of insertion of inputs, the resulting AVL tree will always be the same?

>> No.9657356

I'm going back to school at 27 will all the freshman make fun of me?

>> No.9657513

>>9656200

T = 1/r so it must be curvature.
https://en.wikipedia.org/wiki/Radius_of_curvature

>>9656207
>>9656468

Can't be, units are wrong. Unless they meant to write v = ωr = 2πfr = 2πr/T and they typoed n (frequency) with the r at the end.

>> No.9657519

>>9656439
Out of practice
Sloppy because you think its below you and don't pay enough attention

>> No.9657523

>>9656540
You flip one of them around and its easier to see with the unsymmetrical ramp.

>> No.9657526

>>9656575
Protons, Neutrons
Quarks, Gluons

>> No.9657531

>>9657356
No, nobody bullies anyone in college. (Except feminazis and sjws, but you won't be interacting with them.)

>> No.9657567
File: 133 KB, 1902x709, response.png [View same] [iqdb] [saucenao] [google]
9657567

You're welcome

>> No.9657774

Biofags, answer me this: Do our brains actually run on some sort of "raid 0", copying stuff from one side to another? If yes, will I still be ok if I safely shut down half of my brain?

>> No.9657801
File: 32 KB, 231x234, 6ae8e4fb5329900d696b5bde2c37b644.jpg [View same] [iqdb] [saucenao] [google]
9657801

If you were to add up all possible 24 hr times on a clock, what is the average time?

>> No.9657849
File: 40 KB, 720x736, 1521022761280.jpg [View same] [iqdb] [saucenao] [google]
9657849

>>9656198
Can anyone recommend a website online/Jewtube where I could learn Linear Algebra on its full expansion without a book? Thanks
T. broke fag.

>> No.9657852

>>9657801
4:20 obvi

>> No.9657883

>>9657849
http://4chan-science.wikia.com/wiki/Obtaining_textbooks
http://4chan-science.wikia.com/wiki/Mathematics#Linear_Algebra

>> No.9658682
File: 21 KB, 638x369, sz0XL[1].png [View same] [iqdb] [saucenao] [google]
9658682

So I want to make an electric shock generator device for shits and giggles.
I found this schematic on the internet and I understand most of it except the capacitor.

What does the capacitor do here?

>> No.9658694

>>9658682
Low internal resistance so it can deliver very high instantaneous current when you short it out. Voltage sources like batteries usually have relatively high internal resistances that would limit the current to a few amps without the resistor in series and that may not be enough to either develop a high enough voltage on the output or to sustain the high voltage long enough for you to actually feel it.

>> No.9658697

>>9658694
>Voltage sources like batteries usually have relatively high internal resistances

Then why is a resistor in series there?

>> No.9658698

>>9658682
My guess its a dc-link, dc-bus thing which maintains the voltage supply under load changes. Where the load change would be putting it on your skin.

>> No.9658704

>>9658697
Probably to avoid directly shorting the supply. That's generally not good for batteries and things like that.

>> No.9658707

>>9658698
It's not. When you press that button the capacitor is directly connected to through that winding of the transformer (basically a short). The voltage across the cap will drop right down to zero very fast.

>> No.9658716
File: 15 KB, 207x243, file.png [View same] [iqdb] [saucenao] [google]
9658716

why is Riemman's zeta function undefined at s=1?

>> No.9658723

>>9658716
1/(n^1) doesn't converge

>> No.9658724

>>9658716
It's not undefined; you would say it diverges to infinity. You could also say that it crosses the y-intercept at -1/12.

>> No.9658725

>>9658723
and why does 1+1+1...+1 do?

>> No.9658768

>>9658725
it doesn't
analytic continuation is a thing
https://youtu.be/sD0NjbwqlYw?t=10m

>> No.9658801

are we in a recession or? still a bull market?
i have noticed on my country's equivalent of ebay that buyers have become a lot more stingy than usual. lots of items go unsold. most buyers are only looking for a super deal and won't pay anywhere near the "fair price". some items like smartphones which are always in demand go for higher prices than usual but only because there are so few of them to go around - because people are holding on to their old phones instead of upgrading to a new phone and selling their old phone?

>> No.9658844
File: 146 KB, 914x1249, 8360143b2ab9fbc12f4be3f9de298e17.jpg [View same] [iqdb] [saucenao] [google]
9658844

Is there a "stronger version" of heroin like how heroin is a "stronger version" of morphine?

>> No.9658859

>>9658844
https://en.wikipedia.org/wiki/Ohmefentanyl

>> No.9658861

>>9658844
I wanna say fentanyl is stronger maybe but I wouldn't know, I'd don't do shit like that nor do I ever plan to.

>> No.9658876

>>9658844
https://en.wikipedia.org/wiki/Carfentanil

>> No.9658884

How do I bin data?

I have many data points following a log function and would like to bin them in some interval to reduce the number of data points.

Do I just fit a log function to the complete set and use that functions value at a certain variable value as the data?

Must I do this fit separately in each interval or should it be the same fit for all intervals?

>> No.9658898

>>9656823
> why is the reflection in the definition?
Because it makes convolution symmetric: f*g=g*f.

>> No.9658899

>>9658876
while technically "stronger" this doesnt count as there is no dosage low enough to work on humans without killing them.

>> No.9658905

>>9658844
Heroin is Diacetyl mopheine, just oxygenated mopheine.
There are many opiates and many that are stronger than heroin. I used heroin for years. Although I rarely found it, I preferred the euphoria of oxymorphone out of all the opiates.

>> No.9658920

>>9658801
IDK about your country specifically but the world is in a sustained bull market.

Deal is Amazon probably took your business, they even sell used crap now.

>> No.9658971

>>9658768
so if it doesn't when s=1 why can you define a value for the series at s=0 which is -1/12? is this an approximation?

>> No.9659072

also, is it not possible to solve the Navier-Stokes equations in 3D analytically? that's what the Clay prize is about right?

so CFD codes just solve them using FVM, giving a solution to some test function rather than solving the PDEs directly no?

>> No.9659292

>>9658971
the video is very good

>> No.9659298

>>9659292
yea i watched and the channel is top tier, I think I understand now although I do not know what analytic continuation really is

>> No.9659540

Can I go into cryptography with a Applied Math degree and Comp Sci minor? Or do they usually prefer Pure Math grads? My school has an accelerated BS/MS program for applied math and I was planning on applying to that Junior year.

>> No.9659550

Out of curiousity do medical students ever use any of their orgo shit? I've taken a look at the things you actually do for med school and you honestly just seem to need decent high school level sciences and you're set.

>> No.9659583

>>9659550
Med students are notorious memorizors and cheaters. Being a doctor nowadays just means having stored all the information in your head before an exam.

I haven't taken biochem, nor do I plan to, but I'd imagine they reference things like oxidation/reduction, salt and pH concentrations, but probably not much beyond that. I mean, you can get away with understanding how hemoglobin binds oxygen and carbon dioxide to the iron center without knowing a lick or inorganic chemistry. And it's not like you need to understand it anyway, you can memorize and cheat like everyone else.

>> No.9659592

>>9659540
From my understanding, cryptozoology requires much more rigorous maths then what you will find in an applied math degree. With that said you may want to consider that accelerated masters program.

>> No.9659600
File: 18 KB, 819x819, 44AD7DA6-F55A-45B6-85FE-64A878A03247.gif [View same] [iqdb] [saucenao] [google]
9659600

What if a jet did not replicate a quark to replace the quark that was sent out of the nucleon?

>> No.9659606

I'm bad at math and always have been and my classes want me to do proofs which I really hate

>suppose A is a square matrix such that A^2+A=I
>prove that A is invertible and find the inverse

My answer is
>If A^2+A=I then A(A+I)=I
>Suppose that A did not have an inverse, then there would be no expression for X that satisfies AX=I. However, since A(A+I)=I, A+I would be an expression for X, so A is invertible (and its inverse is A+I)

I tried to sort of copy the type of language used in proof examples. A lot of proofs shown to me have been very clean deduction proofs that just go step by step with no break but my answer doesn't do that. And I guess I'm not totally clear how I really actually said anything about the existence of A^-1. All I said was basically "you gave me an equation where AX=I so yeah no shit X is going to be A^-1". Does that actually prove that A is invertible? I mean what else do I even have to work with, if the original equation A^2+A=I is true then I'm good right? Or do I have to do more work like have it in the form I=A^-1-A and then directly show that A^-1-A=AA^-1 without using any inverting?

>> No.9659614

>>9658905
>I used heroin for years
The way people talk about it it sounds like being addicted to heroin is basically the end of your life
Where are you now, how bad was it and how hard was it to stop using

>> No.9659616

>>9659606
>Suppose that A did not have an inverse, then there would be no expression for X that satisfies AX=I. However,
Leave this out of your answer

>> No.9659627

>>9657356
This is what I'm scared of if I end up dropping out and then wait a few years then want to come back
I'm a good normal age for my year now but I would hate being older...

Though I think being worried about this shows good sense; there's this one guy in my physics lab who's like 30 and has a giant beard and always really loudly talks about his wife and 3 kids, it's like he wants everyone to know how old he is in this sophomore course. Like he's glad he's old and thinks everyone is impressed by it. Everyone thinks he's a giant ass. So you being the opposite of him in terms of attitude means people won't think you're an ass.

>> No.9659630

>>9659616
yeah that's also what I was thinking i
it seems too simple though
(this question is a lot of points and its not even the first one, all the others are hard i dont know why this would would be easy)

>> No.9659842

Does anyone know of an animation of this
My brain really REALLY needs to be able to see the viewing plane move back and forth. Like what if the plane was behind the cube, I can't picture what the projection would look like

>> No.9659845
File: 103 KB, 1280x988, 1280px-Perspectiva-1.svg.png [View same] [iqdb] [saucenao] [google]
9659845

>>9659842

>> No.9659864
File: 920 KB, 2480x1748, tinnitus-poll.jpg [View same] [iqdb] [saucenao] [google]
9659864

How can we better understand tinnitus and potentially even cure it?

>> No.9659993
File: 17 KB, 838x293, Determinante 3x3.png [View same] [iqdb] [saucenao] [google]
9659993

lets say we have a 3x3 matrix. How can we prove that the determinant of it can not be the sum of 6 positive numbers? I am having trouble finding out a relatively smart way of solving this- pls help

>> No.9659999

Is there a general method to find the indefinite integral of the reciprocal of a function?

>> No.9660061

>>9659845
Moving the projection plane simply changes the scale factor. Moving it to the opposite side of the viewpoint negates the scale factor (i.e. the projected image will be rotated 180 degrees).

>> No.9660145

>>9659993
The determinant is the sum of 6 terms, of which 3 are negated. If all elements are positive, then you have 3 positive terms and 3 negative terms. So you have an odd number of positive terms. Each element appears in exactly two terms. Flipping the sign of one element flips the sign of two terms, so the number of positive terms remains odd. Thus you can't have 6 positive terms.

Also, if any of the elements are zero, you will have at least two terms which are zero regardless of the signs of the other elements, so you can't have 6 positive terms (although you might be able to have 6 non-negative terms; I haven't checked).

>> No.9660227
File: 82 KB, 348x278, 1517950088819.jpg [View same] [iqdb] [saucenao] [google]
9660227

>>9660145
I was thinking that was the right way to go, but i assumed there was more to it. (guess i'm an idiot) Thanks for the answer man.

>> No.9660274
File: 43 KB, 647x397, Screenshot_20180409-175852.jpg [View same] [iqdb] [saucenao] [google]
9660274

Is there a way to find the inverse of this other than gaussian elimination? I think I would have to convert everything to fractions and work from there and it would get messy even then.
Or I mean like, is there something simple I'm missing so that this won't just be tedious

>> No.9660316

>>9660274
The other way you can do it is with the Adjoint method, but that will be tedious with a 4x4 matrix. You could also augment the matrix with the identity matrix and transform [math] [\textbf{A} | \textbf{I}] [/math] into [math] [\textbf{I} | \textbf{A}^{-1}] [/math].

>> No.9660346

>>9660316
which would still have you doing elimination. but gauss-jordan is easier to keep track on

>> No.9660355

>>9660274
Multiply the matrix by 10 and you can invert a matrix of integers (and at the end of it you multiply by 1/10). It's not more messy than inverting any 4x4 matrix.

>> No.9660399

>>9660274
There are various ways to invert matrices, but Gaussian elimination is generally the preferred general-case method when dealing with "easy" numbers (integers, or fractions with a small GCD).

Cramer's rule is simple and stable but inefficient, block-wise inverse can be useful if the matrix has a certain structure (e.g. if a substantial submatrix is diagonal).

>> No.9660539

I'm like halfway through my linear algebra course and I'm still stuck on finding the basis. I have an A but I have no idea what's going on. The homework is nothing like the quizzes/tests, and the lecture slides don't make sense to me.
I have a test Thursday on eigenvalues/vectors and diagonalization, and I can find the vectors but I don't understand what any of this does.
Am I doomed to only know high school algebra?

>> No.9660549

>>9660539
>I'm like halfway through my linear algebra course and I'm still stuck on finding the basis.
This is a genuine difficulty since most vector spaces do not have a basis.

>> No.9660962
File: 30 KB, 274x270, 1511116743548.jpg [View same] [iqdb] [saucenao] [google]
9660962

I hate to be someone asking to be spoonfed but I am taking differential equations right now and everything has been clear to me up until this point. I really don't understand how to draw the phase portraits for solution matrices with complex eigenvectors and eigenvalues. I don't know why I can't figure this out. How does A:= matrix( [[1, -5 ] , [1, -1]]) end up with this phase portrait?

>> No.9660966

>>9656198
What's a good way to make sure I don't have any holes in my elementary algebra? Do you know of a problem repository that's particularly tricky?

I finished chapters 1-2 in Spivak awhile ago, and that really squeezed out most of my rust, but a resource I could run through every now and then would be great.

>> No.9660978
File: 95 KB, 578x575, Screenshot from 2018-04-10 00-50-54.png [View same] [iqdb] [saucenao] [google]
9660978

>>9660962

>> No.9660988 [DELETED] 

>>9660978
Fuck I still don't understand this. My professor is going to be so disappointed.

>> No.9660997
File: 111 KB, 1196x776, duPPi.png [View same] [iqdb] [saucenao] [google]
9660997

>>9660988
Try this.

>> No.9661021

Just popped onto this board, but would I be correct in saying that the flat-earth theory is wrong based on the fact that gravitational acceleration can be slightly different based on your location on earth. where if the flat earth was accelerating at 9.8m/s^2 up then it would not change depending on where you are, right? Am I right in assuming that there are no crazy movements the "flat-earth" could make to account for that?
and if this is the case, why is this not the #1 way of disproving the flat-earth theory? it is so simple and can't really be explained away by flat-earthers. (unless I am wrong in assuming that)

>> No.9661028

>>9661021
I don't get what the benefit of having a flat earth model is if you have to say it's accelerating up, that would mean space exists and an outside universe exists. I thought the point of flat earth was that earth is the center of the universe etc. If you're just gonna say that we're on a flat plane moving around in space, I mean is that really too radically different from a sphere moving around in space from a conspiracy perspective? The only difference is gravity possibly not being a thing, which is kind of inconsequential.

>> No.9661044

>>9661028
idk I don't come up with this crazy shit, that's what flat-earthers believe, that it is being accelerated by an aetheric wind. and that is why we have a perceived acceleration that we think is gravity. but my question was, isn't it easily disproven by the fact that gravity isn't exactly the same everywhere on earth?

>> No.9661045

Why do asians saturate every booming field and drive wages down

>> No.9661053

>>9661021
No.

>> No.9661066

>>9656207
how is a woman's period have anything to do with speed?

>> No.9661077
File: 7 KB, 183x275, download (8).jpg [View same] [iqdb] [saucenao] [google]
9661077

>>9656439
>>9656482
>he thinks calculus is advanced math

>> No.9661081

>descriptions of hell from hundreds or thousands of years ago match what scientists are discovering today about conditions near the center of the earth

checkmate atheists

>> No.9661086

>>9661081
they found an ice lake in the center of the earth?

>> No.9661091

>>9657198
Go do your homework somewhere else

>> No.9661131
File: 11 KB, 800x600, Flat Earth Diagram.png [View same] [iqdb] [saucenao] [google]
9661131

>>9661021
I only know a little bit of classical mechanics, so I could be wrong here, but if we consider earth to be flat we could still take the center of mass and apply the normal inverse square law. If you go further away from the center of mass, the force of gravity would decrease (see poorly drawn picture). Since the top is flat, though, the further out you go the more sideways you'd have to stand to have your feet pointing to the center of mass, so everything would have to be super tilted at the edges (again, see picture).

>> No.9661170

thank you for always being so helpful sqt i only ever ask questions because im a brainlet but thanks!!

>> No.9661175

are there alternative systems that attempt to make more intuitive sense of the square root of a negative number? You (obviously?) ould need something analogous too multiplication being defined non-competitively (as in -x*x=x, but perhaps x*-x=-x), and this would proceed to have the square root defined differently, and likely a host of further implications but I'm out for the night, rip /sci/

>> No.9661180

>>9657774
No goes in all fields.

>> No.9661207

>>9661180
good thing you're not a programmer

>> No.9661210

>>9656439
probably because your defined advanced math wrong, or have only faced ezpz problems

>>9656482
Calculus is just the application of algebra and geometry. Being a mechanic is more difficult to learn than being a driver.

>> No.9661211
File: 17 KB, 600x434, 1522429084160.jpg [View same] [iqdb] [saucenao] [google]
9661211

>>9660997
>degenerate sink

>> No.9661212

[math]\sum_{n=i}^{n=j}\frac{\frac{n(n-1)}{2}}{n} [\math]
you have to define n, i and j though, and this is where your question becomes...
>ill defined

>> No.9661215

>>9661212
>>9657801
[math] \sum_{n=i}^{n=j}\frac{\frac{n(n-1)}{2}}{n} [\math]

>> No.9661216
File: 5 KB, 202x188, 1446633303789.png [View same] [iqdb] [saucenao] [google]
9661216

>>9660997
>degenerate source

>> No.9661220

>>9661212 (Me)
>>9657801
>>9661215
pasted the wrong one last time:
[math] \sum_{n=i}^{n=j}\frac{\frac{n(n-1)}{2}}{n} [/math]

>> No.9661224

>>9661220
the denominator N should divide the sum, not be included in the sum tho

>> No.9661233

>>9657567
I hate when this happens

>> No.9661267

How many hundredweights of apparent mass will 63 gil of water have if gravity acts on the water at 1.3 nautical miles per minute and a force of 17 slugs is applied at an angle of 33 degrees from the x-axis?

Please help this is standard British question.

>> No.9661275

>>9656198
hi,

what do you call the cell extensions on either side of a bidirectional chemical synapse?

like an axon dendrite hybrid mix?

>> No.9661573

AI exam in a few hours, do I sleep an hour or stay awake. Logically I am thinking I stay awake but boy does sleep sound nice rightnow.

>> No.9661588

>>9656439
what do you mean you struggle with basic math, like you cant add 2+3 despite trying your best? If you mean careless mistakes, thats just what it sounds like. Solving some calc or linear algebra problems is your primary concern, its easy to rush through the basica arithmetic and fuck something up without realizing. Doing linear algebra stuff by hand was a nightmare for me because I forgot a negative or something along the line 60% of the time and never realized until I realized that there was no way the problem was so hard and started over.

>> No.9661590

Have we found a way to clone organisms that includes mitochondrial DNA? If so, why do we call the offspring of said organisms as "clones" when they are not completely identical thanks to only having identical nuclear DNA (and also mutations)?

>> No.9661608

Is anyone here from Stanford? If you are taking the Fourier class mind sharing with me the sinesum2 app? Kthz

>> No.9661951

>>9661275
>hi,
lmao

also it's just an axon

>> No.9662093

I had a dream about taking a Fourier transform of a horizontal solenoid and getting back a vertical solenoid. But I don't actually know what a Fourier transform even is. What's a Fourier transform?

>> No.9662127
File: 265 KB, 300x240, fourier transform.gif [View same] [iqdb] [saucenao] [google]
9662127

>>9662093
it decomposes a function into its frequencies ("frequency domain representation")
it's a complex valued function as well, magnitude is the amount of frequency shown in the original function (for any cos(x) graph there's also an i*sin(x) graph since it uses the e^ix identity), and the arg of the function (or the angle t in |r|*e^it) is the phase angle or offset

i could explain further i guess but i don't know how much you want to know

>> No.9662148

>>9662127
So you have a complex wave, which is just a superposition of a bunch of other waves added together, and then you plot the component waves based on their frequency and amplitude?

>> No.9662174

>>9662148
no you have a real wave, however there's a hidden complex part
if you have something like Acos(wx+p), it can be represented as Re[Ae^(i(wx+p))], and if it were Asin(wx+p) it'd be the same thing but Im[] instead
the plot at the end is essentially dirac delta distributions with peaks at the different frequencies

if you understood everything i've said to this point you may as well read the wikipedia article on it https://en.wikipedia.org/wiki/Fourier_transform

>> No.9662205

Some random dumb questions.

Why, exactly, is it harder to peddle a bike uphill than it is to walk or run up a hill with the same amount of speed?

Also, say they bring back hydrogen-filled airships. Is there anything they can add to the hydrogen to make it not burn or explode so easily? Dilute it with helium or nitrogen or some gas that prevents it from burning?

You have a window A/C unit like you see in the western hemisphere. If these are simply heat pumps, can you simply turn it backwards in the window so it works like a heater in the winter? If so, why does nobody do this?

>> No.9662242

I'm not expert on the shit but:

>>9662205
>You have a window A/C unit like you see in the western hemisphere. If these are simply heat pumps, can you simply turn it backwards in the window so it works like a heater in the winter? If so, why does nobody do this?

Yes and no. There are A/C like that but shit is expensive and its service time lower because the heat-exchange unit construction differs for cooling and heating.

>Why, exactly, is it harder to peddle a bike uphill than it is to walk or run up a hill with the same amount of speed?

Pretty sure you can google extensive answer for that, anon.

>> No.9662261

>>9661045
There are 45 grad students in my department
1 black mab
0 black women
3 white males
5 white women
3 pajeet men
0 pajeest women
24 asian men
9 asian women

>> No.9662277

>>9662261
>"There are x students in Class1. It is known that Class2 has 1.5 more students than Class3, and Class3 has twice the amount of students of Class1. Find exact amount of students in each class if it is know that the department contains Y students total"

>> No.9662285

>>9662148
It can be shown that any repeating function can be represented by sum of sines.
Now consider the fact that a given function is repeating, knowing one cycle of the function is enough to describe the entire function. Then you really don't care about the time. Fourier Transform is a transformation from time domain to frequency domain.
So if your original function is a sum of 10 sines, instead of saying, at time k I have amplitude a_k. I just ask, given any period, what is the frequency and amplitude of the first sines? What about the second sine? Ask these for all 10 sines and you have yourself a Fourier graph.

>> No.9662298

>>9662285
not him but that was an A+ explanation
i go to a shit school, the explanation our prof gave was "dont worry about what it does, just use this list of transforms for the test"

>> No.9662299

>>9662205
For the bike question, I would wager it's due to the fact that there are less friction stopping your from rolling down so you have to constantly exert force to maintain your upward velocity.

>> No.9662350

>>9662299
This is what I assumed and I looked it up. Since gravity is making the bicycle roll backwards and bicycles have very little rolling resistance. You would roll backwards without peddling and that force has to be actively foguth again. it's harder than walking, since your feet don't have to actively fight gravity, you can ratchet up the hill by walking without gravity pulling you backwards.

Also I found bicycles are not geared to go slowly up hills, putting maximum effort into peddling is the most efficient way and frankly, fuck that.

I was hoping to find an equation, but I don't care that much I suppose.

Still wondering about using an A/C unit as a heater, though.

>> No.9662365

>>9662205
>Why, exactly, is it harder to peddle a bike uphill than it is to walk or run up a hill with the same amount of speed?
Depends on your gearing. I rock a 50 cassette, going up 7% grades is nothing compared to trying to run up it

>> No.9662591

How do I know if I'm smart?

>> No.9662717

https://www.space.com/40255-hubble-telescope-einstein-ring-photo.html

Is this redshifting? If so.is this the first time its been had a photo taken of the phenomenon
Sorry for popsci brainlet here

>> No.9662759

does a number to the power of an irrational number have a positive and negative answer

>> No.9662913

>>9662591
maybe having the skill for knowing if your smart requires you to be smart

>> No.9662993

>>9662591
if you have to ask, you're not

>> No.9663035
File: 75 KB, 853x784, Screenshot_2018-04-10_20-17-01.png [View same] [iqdb] [saucenao] [google]
9663035

stuck on this proof of Pappus' theorem. How is it deduced that [math]BC^{\prime}\cap B^{\prime}C[/math] is represented by [math](1,1,1)-(1,c,0)[/math], likewise for the other intersections?

>> No.9663138

What is a really good book on plane trigonometry? One that focuses on proofs/geometric problems, with little to no physical applications.

>> No.9663170

>>9663035
i don't get it
the lines (0,1,0)(0,0,1) and (1,1,1)(1,c,0) don't intersect for any value of c

solve it yourself, (0,1,0)+L(0,-1,1)=(1,1,1)+L(0,c,-1,-1) for no value of L

(0,1-c,1) only falls on either line at c=1, and it's obvious which line that is

>> No.9663187

>>9663035
If a point on B'C is also in BC' then it must have x_0=0, which is only satisfied by (1,1,1)-(1,c,0)=(0,1-c,1)

>> No.9663189

>>9663170
>the lines (0,1,0)(0,0,1) and (1,1,1)(1,c,0) don't intersect for any value of c
This is false.

>> No.9663214

>>9663189
(0,1,0)+L(0,-1,1)=(1,1,1)+L(0,c,-1,-1) doesn't have a solution though

>> No.9663226

>>9662759
A number to the power of an integer is a number. A number to the power of a fraction is a solution to an implicit equation, and there are as many solutions as the denominator. E.g. y=x^(4/3) => y^3=x^4, which will have 3 solutions, two of which are complex (assuming x is real).

If the exponent is irrational, then there will be infinitely many solutions, lying on a circle in the complex plane; at most one of these will be real. The points will form a sequence whose arguments (angles) are multiples of 2*pi*k (where k is the exponent). If k is irrational, it's impossible for an integer multiple of 2*pi*k to be an integer multiple of pi, i.e. it's impossible to have two real solutions.

>> No.9663228

>>9663214
>(0,1,0)+L(0,-1,1)=(1,1,1)+L(0,c,-1,-1) doesn't have a solution though
(0,1-c,1) is in both BC' and B'C.

>> No.9663314

>>9661590
>Have we found a way to clone organisms that includes mitochondrial DNA?
No. There are methods of fertilization that involves taking genetic material from a male and female and putting them in a donor egg so that the baby will have the mitochondrial DNA of the egg donor. A similar method could probably be used in cloning, but only of females.

>why do we call the offspring of said organisms as "clones" when they are not completely identical
Same reason "tin foil" is made of aluminum or "shooting stars" are not stars. Names are created for things and sometimes those names imply things are true when they're not.

>> No.9663394

Let [math]\varphi : \mathbb{R}^n \to \mathbb{R}[/math] be the linear functional [math]\varphi ( x_1, x_2, x_3 ... x_n ) = x_1 + 2x_2 + 3x_3 + ... + nx_n [/math]
By Riesz-Representation, there is some unique vector [math]u \in \mathbb{R}^n[/math] so that [math]\varphi(v) = < v, u >[/math]

A) Sorry if the formatting isn't right, I can't actually preview TeX for some reason
B) Would the resulting u be:
(1, 2, 3, 4, 5, 6 ... )
or
( 1 * (1, 0, 0, 0 ...) + 2 (0, 1, 0, 0 ... ) + 3 etc
?
Would it be the second because it's just linear combinations of the standard basis? But I thought u was meant to be a unique, single vector? Or is that just a more verbose way of saying the first?

>> No.9663405

>>9663394
>B) Would the resulting u be:
>(1, 2, 3, 4, 5, 6 ... )
>or
>( 1 * (1, 0, 0, 0 ...) + 2 (0, 1, 0, 0 ... ) + 3 etc
>?
>Would it be the second because it's just linear combinations of the standard basis? But I thought u was meant to be a unique, single vector? Or is that just a more verbose way of saying the first?
Those are the same vector.

>> No.9663454
File: 894 KB, 1350x755, Untitled.png [View same] [iqdb] [saucenao] [google]
9663454

What parts of the brain are used when looking at this image and generating an unnerving feeling? Also, I'm curious if other animals, when shown similarly warped versions of themselves, produce the same response.

>> No.9663458

>>9663405
Okay that's what I thought, thanks

>> No.9663476

>>9663454
facial recognition, disconnect between parts of brain that attempt to identify an object, memory and heightened senses due to increase in stimuli (e.g. tons of detail (hyperreal) or music that appears to "lead" to something)

most of it is really just a failure to identify something as one or the other, which is why a creepy object becomes less creepy over time

>> No.9663730
File: 39 KB, 640x360, original.jpg [View same] [iqdb] [saucenao] [google]
9663730

Here's a quick dumb question.
I was thinking about skydiving and if two people were close to each other, could one of them pull the other close to them. Kinda like pic related. If the people were to grasp each other's hands and the person above wanted to pull the other person close, how "heavy" would they feel?
Like if they are going at terminal velocity, would they be "weightless" and and fairly easy to pull or would it be like trying to pull their entire weight like pulling someone up from the edge of a cliff.

>> No.9663744

>>9662993
Are you sure about that?

>> No.9663827

>>9663454
my guess would be mainly that the warping and black patches are processed by your brain as severe injuries (as if you're looking at a mangled corpse), which naturally gives your fight-or-flight response a little poke

>> No.9663833
File: 40 KB, 618x812, 1523399273023.jpg [View same] [iqdb] [saucenao] [google]
9663833

>>9663730
You would pull yourself to them.

>> No.9663839

>>9663730
Let's make it simpler. There are two people floating in space, and so they are totally weightless. If one grabs the other and pulls, he would still feel the inertia from the other person's mass. The acceleration of one to the other would be proportional to the force applied.

>> No.9663912

when integrating in spherical coordinates why is the integration in order (p,phi,thetha) instead of just whatever, like in xyz coordinates

>> No.9664105

if nothing travels faster then the speed of light, why do black holes exist? how is gravity exerting enough force to keep light from escaping?

>> No.9664122
File: 15 KB, 350x200, phone-heat.jpg [View same] [iqdb] [saucenao] [google]
9664122

I use my phone a lot at home but it frequently gets as hot as 30°C. I damaged my previous phone battery when the phone become 35°C hot for just a few minutes.

To cool down the phone I stop using it for a few minutes and place it on a table surface or something with the screen off. But is there a better method to cool down a overhot smartphone or laptop without placing it in a fridge or placing it outside for a short time?

I once placed it on top of a large sheet of aluminum casing from my old computer and it cooled down real fast. What's the best metal surface for chilling hot objects placed on it?

>> No.9664166

>>9656198
Ill be here if anyone wants help with anything calculus, im not a genius but maybe i can help you with anything.

>> No.9664185

>>9664122
put it in cold water

>> No.9664194

Is keto legit I've been trying to read up on carbs and limitation of them in the diet, also how it could be linked to things like Alzheimer's but then you read about fats and stuff causing it too. I'm nit overweight by any means and I'm not against it I just can't find a good enough reason to avoid carbs like I try to avoid refined sugars.

>> No.9664209

>>9664122
Wrap in aluminum and put it in front of a fan. Or sit it under an ice pack with the phone in a plastic bag.

>> No.9664354

How many months would it take for me to complete Stewart's Algebra and Trigonometry? I'm currently at page 131 out of 900(complex numbers)

>> No.9664365

>>9663912
The order of integration doesn't matter - Fubini's theorem

>> No.9664456

is
f(x) (dy/dx)^2
equal to
f(x)''

>> No.9664476

Hubble's law states that the recessional speed of a galaxy relative to us is directly proportional to its distance from us.

Why doesn't this mean that galaxies really far away from us are moving away faster than the speed of light?

>> No.9664487

>>9664456
No

>> No.9664600

How would one go into applied math research without becoming a professor? I am assuming that some companies hire mathematicians for R&D and working as a mathematician at a Pharmaceutical company makes my dick hard but I don't know if that's a likely career option to bet on. Should I just go into operations research (which I know isn't the same thing) ? This is a stupid question, I know that's why I posted it here.

>> No.9664601
File: 1.26 MB, 1440x1421, 1522923414930.png [View same] [iqdb] [saucenao] [google]
9664601

>>9664456
derivative squared is not equal to the second derivative

>> No.9664929

Have a linear algebra exam tomorrow on eigenstuff and diagonalization. I can compute stuff but getting the information to set it up and read the computations as an answer I struggle with. I think it's cause we didn't really go over the theory so I'm not getting the why of how we do things.
Is there a video lecture on these that you could recommend so I can do decent tomorrow?

>> No.9664951

how can i show a series [math] \sum a_n [/math] converges if [math] \lim\limits_{n\to\infty}\frac{|a_{n+2}|}{|a_n|}<1 [/math] (from the ratio test rather than by definition)? I think [math] \lim\limits_{n\to\infty}\frac{|a_{n+2}|}{|a_n|}<1\longrightarrow\lim\limits_{n\to\infty}\frac{|a_{n+1}|}{|a_n|}<1 [/math] is what i'm trying to prove.
Im sure it's obvious, but i cant see how to prove it.

>> No.9664956

>>9656439
It a different way of thinking, I've got the same

>> No.9665014
File: 8 KB, 402x49, km.jpg [View same] [iqdb] [saucenao] [google]
9665014

>>9656198
Anyone help me here? I can't figure out how to simplify this expression. The answer is log(x^2 / (x+1)^3 ), but I can't figure out how.

>> No.9665031

>>9665014
What have you tried?

>> No.9665037

>>9656200
TIME

>> No.9665044
File: 1.96 MB, 4032x3024, IMG_2336.jpg [View same] [iqdb] [saucenao] [google]
9665044

>>9665031
I think for the 1/3 log(x+2)^3 I can simplify it as log(x+2), and then for the right side I've got this. Have I made any mistakes or is this the right first step?

>> No.9665048
File: 3 KB, 535x439, jm.png [View same] [iqdb] [saucenao] [google]
9665048

>>9665044
sorry, no clue why 4chan rotated my image. here maybe this is easier to read.

>> No.9665053
File: 2.82 MB, 4608x2592, 20180411_205913.jpg [View same] [iqdb] [saucenao] [google]
9665053

>>9665014
Sorry for the bad handwriting. Are you sure that answer is correct?

>> No.9665054
File: 1.87 MB, 426x426, american education.gif [View same] [iqdb] [saucenao] [google]
9665054

>>9657356
Same except I'm 25 and don't have a real plan to get back yet.

>>9657531
What worries me the most is that people will judge me for finishing so late. I know when I was in college I judged the fuck out of anyone who looked too old to be there; I thought, man, what losers. I don't think I was wrong, and my classmates won't be either if they come to the same conclusion about me.

I guess it's not like I really plan on talking to anyone. I am far too mature to hang out with babies anyway. Haha who needs people, right?

>> No.9665066

>>9665053
Ah no, that wasnt the correct answer. It is indeed listed as log(x^2/x-3). Thank you very much, anon.

>> No.9665070

>>9665054
>who looked too old to be there

That's really for people over 40

>> No.9665073

>>9665014
i got the same answer as >>9665053
also, in>>9665044, you dont divide the logarithms themselves

[math] \begin{align}\frac{1}{3}\log(x+2)^3+\frac{1}{2}\left\{\log x^4-\log(x^2-x-6)^2\right\}&=\log(x+2)+\frac{1}{2}\left\{\log\left(\frac{x^2}{x^2-x-6}\right)^2\right\}\\&=\log(x+2)+\log\left(\frac{x^2}{x^2-x-6}\right)\\ &=\log\left(\frac{x^2(x+2)}{x^2-x-6}\right)=\log\left(\frac{x^2(x+2)}{(x+2)(x-3)}\right)=\cdots\end{align} [/math]

>> No.9665079
File: 13 KB, 255x216, enlightened.png [View same] [iqdb] [saucenao] [google]
9665079

>>9665073
Thank you, kind anon.

>> No.9665133
File: 36 KB, 500x719, 1497135793911.jpg [View same] [iqdb] [saucenao] [google]
9665133

>>9665079
never forget your log laws again, or i'll punish you

>> No.9665300
File: 50 KB, 658x442, Untitled.png [View same] [iqdb] [saucenao] [google]
9665300

Why can we divide by [math] X'(x)+X(x) [/math] in the third to last line?
I understand that we can divide by [math] X(x) [/math] and [math] T(t) [/math] as we assume they are non-zero to avoid a trivial solution, but i'm not sure why the above is possible.
in fact if [math] X(x)=\alpha e^{-x} [/math], which is always non-zero, then [math] X'(x)+X(x)=0 [/math].

>> No.9665301
File: 49 KB, 625x350, many-worlds-head-625x350.jpg [View same] [iqdb] [saucenao] [google]
9665301

Hi /sci/, brainlet here, asking about the most brainlet theory of QM. If our universe is deterministic and there is no free will, then doesn't that mean that the name "many-worlds" is a misnomer since there is no difference on a macroscale between the realities? What the hell does "all possible histories" mean when causality destroys any chance of anything happening differently?

>> No.9665316

>>9665300
if X' + X = 0 then X'' T = 0. so either X'' = 0 or T = 0.

if X'' = 0 then X' = c (some constant) and X = cx+d, so X' + X = c + cx+d. but if X' + X was supposed to be 0 then c+cx+d=0, so c=0, and d=0, so X=0, so u(x,t)=0.

similarly if T = 0 then u(x,t)=0

>> No.9665350
File: 31 KB, 485x443, 1512666625659.png [View same] [iqdb] [saucenao] [google]
9665350

consider a quadric defined by [math]X=Z(x^{2})[/math] over [math]\mathbb{R}\text{P}^{1}[/math]. How the heck do I show that this only contains the point [math][0:1][/math]?

>> No.9665364
File: 22 KB, 485x443, ijj1aSW.png [View same] [iqdb] [saucenao] [google]
9665364

>>9665350
oh fuck never mind I got it. Forgot that the second entry in the homogeneous coordinate is the projective line

>> No.9665438

>>9665301
The universe isn't deterministic, it had random elements

>> No.9665440

>>9665438
>The universe isn't deterministic

>> No.9665449

>>9665440
Yes, that is precisely what the post you referenced said. Would you care to comment on it?

>> No.9665451

>>9665449
Random elements only apply on the microscopic level and that changes dick on the macroscale.

>> No.9665486

>>9665316
Thank you

>>9663912
it isnt.
it might seem that way since usually there is no nice function for the two angles theta/phi that depends on the distance rho. i imagine it's similar to why dx dy is appears rarer to see than dy dx

>> No.9665835 [DELETED] 
File: 24 KB, 1004x145, derp.png [View same] [iqdb] [saucenao] [google]
9665835

This feels like a really simple problem, but I'm getting a different answer from others.
It's a Binomial distribution right? And the probability of a defect is .01 and they buy 3 packs of 10 so they have 30 disk.
I'm trying to find out the probability of 1 of 30 of the disks being defective.
I'm getting .2242 but everyone else is getting .0127

>> No.9665865

Why aren't parametrics considered multi-variable? I get that there are two functions, and each function on its own is only a function of one variable (e.g. x(t) and y(t)), but when you combine them, aren't there really 3 variables? Is it because there's still only one independent variable?

>> No.9666007

>>9664105
By Fermat's principle, that path light takes is the geodesic of the manifold. In general the geodesic need not be a straight line, and for metrics with singular coefficients there are geodesics which end on itself.
>>9664951
>I think
No. Think about Cauchy-ness.
>>9665438
QM is a deterministic theory. Given a quantum state we can deterministically understand its evolution as long as the "evolution" has a unitary representation.
>>9665451
That's not why QM is deterministic.
>>9665865
Because once you have [math]t[/math] you know [math](x,y)[/math]. The latter aren't variables.

>> No.9666329

Can I make artificial gravity by rotating something really really fast the same way you make artificial gravity by moving something at an accelerating rate?

>> No.9666345

>>9666329
Yes. There are amusement park rides that do this. It kinda sucks.

>> No.9666392

how do i study?

>> No.9666416
File: 610 KB, 2302x1536, 5A2AA821-3278-47D1-B5C7-44E8F0879361.jpg [View same] [iqdb] [saucenao] [google]
9666416

>>9666392

>> No.9666422

>>9665451
>and that changes dick on the macroscale.
proof?

>> No.9666441

What's preventing us from making artificial muscles and tendons? I guess plastic is cheaper and easier to make for prostethics but, why has no one researched making artificial muscle fiber?

>> No.9666511

>>9666416
if only adderall was easy to get in australia

>> No.9666676

I have no idea how space works so this will be some absurd question.
so as far as I understand, the moon formed because our planet slammed into a smaller planet during the early years of the solar system development, right? Why is our planet and the moon so different then. They're both made from the same stuff (right?). They're both the same distance away from the sun. Why is the earth so varied and alive and the moon is basically just a floating giant dead rock?

>> No.9666702

>>9666441
They have and are doing so. If you want to learn more, research in vitro meats to see why it's difficult (it's identical research, just being conducted for different reasons).

>> No.9666729

Does giving blood transfer an identifiable aspects of myself? Don't blood cells have DNA? Could my own DNA be identifiable once it's in someone else?

>> No.9666871

>>9666007
QM has many possible histories but they don't affect the larger world. A different quantum configuration isn't going to suddenly make Oswald not kill Kennedy or something to that effect.

>> No.9666945

quick question regarding 3-phase circuits.
If I have a delta connected to a wye load. Do I just convert the load to whatever the configuartion the source is and then solve for whatever Im being asked to solve?

>> No.9666981

>>9658898
emmm complex field retard

>> No.9667141
File: 13 KB, 644x409, mth.png [View same] [iqdb] [saucenao] [google]
9667141

This must be an easy one but I'm stupid.

How do I invert the function f(x)=x/|x| ?

Wolfram gives me pic related.

>> No.9667142

>>9667141
>How do I invert the function f(x)=x/|x| ?
Why do you think you can?

>> No.9667154

>>9667142
The paper says: Apply any restriction you see fit to the domain to make the function invertible.
Can I assume is a trick question then and just answer it can't be done? I've been trying for past hour.

>> No.9667159

>>9667141
x/|x| = sign(x)

>> No.9667209

>>9658716
The other brainlets didn't bother to give you a good explanation. When s=1, the riemann zeta function is a harmonic series. It is monotonically decreasing, but has been shown to fail to converge to a limiting value by way of analyzing its partial sums.

Suppose that we set the sum of the harmonic series to be some value H.
[eqn]H=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+\frac{1}{7}+\frac{1}{8}+...[/eqn]
You can then modify parts of sum to build a relationship for H and the modified sum. Here, every other ratio is made to be slightly smaller.
[eqn]H\geq1+\frac{1}{2}+\frac{1}{4}+\frac{1}{4}+\frac{1}{6}+\frac{1}{6}+\frac{1}{8}+\frac{1}{8}+...[/eqn]
Collect some terms,
[eqn]H\geq1+\frac{1}{2}+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...[/eqn]
and you can see that we have the harmonic series again, which was assumed to sum to H
[eqn]H\geq\frac{1}{2}+H[/eqn]
but you will see that this is a contradictory statement. Therefore, the only conclusion that can be made is that the harmonic series cannot add to a finite value.

>> No.9667219
File: 390 KB, 500x463, 1504212357357.gif [View same] [iqdb] [saucenao] [google]
9667219

Doing some RLC circuits and I am trying to figure out how to get Bc or Xc (doesn't matter) out of this
Y^2=(Bc-BL)^2+R^2

I also don't know if Bc > BL or vice versa.

I always use tg or sin but I want to learn this way as well.

>> No.9667363

>>9657849
3blue1brown

>> No.9667414
File: 3 KB, 270x91, image.png [View same] [iqdb] [saucenao] [google]
9667414

what's the name for the operation in pic related? it lets you express a ratio as a number between 0 and 100, is there a name for this?

>> No.9667419

>>9667414
percentage?

>> No.9667749

>>9656198
How do you visualize division?
Addition and subtraction are easy: suppose we have x + y. I imagine taking the distance x and concatenating the distance y to it as the sum x + y. Subtraction is similar. I guess i sort of imagine a number line, and situating length-1 vectors on it to add and subtract.
Multiplication similarly is pretty easy: it is repeated addition, so to visualize x * y, I imagine concatenating x with itself y times.
Does this visualization strategy hold for division?

>> No.9667766

>>9667749
>division with remainder
repeated subtraction
>long division
repeated subtraction with fractional subtractions

multiplication is stretching out a line (1 goes to the multiplier)
division is contracting it back (the divisor goes back to 1)

>> No.9667825

Jennifer wants a C in her algebra class, which is 70%. The final grade for the class is made up of two scores, the class grade of all assignments, and the final exam. The class is worth 70% of
Jennifer’s final grade, and the final exam is worth the remaining 30%.
If Jennifer currently has 72/100 on
Her in class assignments, what is the minimum score she needs on her final exam to pass the class if the final is 50 questions?
(The final is 50 questions, for 50 points, and is worth 30% of her total grad.)

>> No.9667855
File: 32 KB, 400x400, red.jpg [View same] [iqdb] [saucenao] [google]
9667855

>>9656198
Is CS a meme degree?
I've done one year of CS and find my self only picking math classes for electables because CS specific ones isn't that interesting. I really only enjoy the freedom and power in programming. I don't give a damn about computer architecture or operating systems desu.
Is it reasonable to switch to physics or something?

>> No.9667948

>>9667766
Most appreciated anon

>> No.9668081

>>9667749
How does your visualisation strategy work when you consider [math] \pi\cdot \pi [/math]?

>> No.9668099

>>9667855
physics bois and math lads end up programming for jobs in the end. Stick it out with cs

>> No.9668136

>>9667141
Can’t you just take a bunch of points, switch x and y, then graph that?

>> No.9668143

>>9668099
I get that. But then atleast I will study something more interesting.

>> No.9668156

https://www.chegg.com/homework-help/questions-and-answers/question-1-let-v-inner-product-space-n-dim-v-93-vi-v2-un-basis-let-v-rn-isomorphism-given--q28189109

Can someone explain this guy's solution, specifically what he is using (ij)^n for?

Dankeschoen

>> No.9668229

>>9667825
Please help this one is fucking me up

>> No.9668637
File: 69 KB, 388x661, thumbnail.jpg [View same] [iqdb] [saucenao] [google]
9668637

>>9667825
>>9668229
I worked very hard on this so I hope you're grateful

>> No.9668913

>>9667855
>>9668143
when you finally go into practical field you will realize how retarded you were skimming over CS stuff

>> No.9668916

>>9668637
>that handwriting

>> No.9668948

>>9656198
How Do I get over my fear of studying?

>> No.9668979

>>9668948
?????????????

>> No.9669037

Why aren't there any rotating space stations out there simulating gravity?

I understand earth's gravity would be a huge pain to simulate, not just because of the stress it would induce on the station but also because microgravity is so liberating for moving around and doing work, among other things. Still, why haven't we tried simulating a more moderate gravity like the moon's that doesn't complicate things as much yet still allows us to study the effects of reduced gravity and how it compares to microgravity?

>> No.9669044

>>9668948
>>9668979
Live a more hardcore life so you stop being afraid of dull shit.

>> No.9669096

>>9669037
A centrifuge needs to be large in order to provide a reasonable approximation to gravity. A small, fast centrifuge will cause moving objects to experience a significant Coriolis force. In humans, this tends to cause dizzyness.

So usable artificial gravity needs a large radius, which means a large craft. Two craft connected by a tether would work (Gemini 11 did this, but only managed 0.00015g), but is more prone to oscillations if there's any movement. Cancelling the oscillations (which is still an issue for a rigid connection) using thrusters would consume propellant fairly rapidly.

tl;dr: it's too expensive to do it at anything beyond "lab experiment" scale.

>> No.9669124
File: 27 KB, 318x416, g.png [View same] [iqdb] [saucenao] [google]
9669124

>>9669037
>>9669096

>> No.9669126
File: 22 KB, 882x214, gauss.png [View same] [iqdb] [saucenao] [google]
9669126

This is the very first question in the "easy section" of a past paper, so its supposed to take about 4 minutes.

And sure enough its very simple to evaluate, but the question wants me to use specifically Gauss' Law to answer it, and I dont see how.

I would just straight-up do the integral, it seems easy enough. I dont understand how Gauss' Law can be used in this case.

>> No.9669131 [DELETED] 

I'm posting this because this could be the last thing I'll ever post.

The city I once knew as home is teetering on the edge of radioactive oblivion, a three-hundred thousand degree baptism by nuclear fire. I'm not sorry.
We had it coming.

A surge of white-hot atonement will be our wake-up call. Hope for our future is now a stillborn dream. The bombs begin to fall and I'm rushing to meet my love.
Please, remember me
There is no more

>> No.9669134

>>9669126
>who's he talking to

>> No.9669152

Anyone here experience being a student on TU Delft?

>> No.9669169

>>9669126
whups never mind
I thought by Gauss' Theorem it meant specifically electromagnetism and I would have to write I as being the surface integral of current density etc

which is wrong
I is just a meaningless letter, it wants you to use the general Divergence theorem which is apparently also known as Gauss theorem - I thought the name "Gauss theorem" was reserved exclusively for EM stuff, which was wrong

>> No.9669250

test

>> No.9669255

Given a professional boxer throws an exceptionally vicious right-hook measuring 700 joules straight into a bumblebee flying in mid-air. In this thought experiment, the bumblebee survives.

What is the mathematical model that explains that the low-mass bumblebee did not absorb all 700 joules in that savage blow and survived?

>> No.9669303

Not an engineer but always wondered, what's the point of rolling steel? Googling only shows results for the differences between cold and hot rolled steel, which I couldn't give less of a fuck. I'm talking about what are those rolls of steel used for? They look so impractical, how are they used to build things?

>> No.9669339

>>9658899
Not necessarily true. If it’s soluble in water you can do successive dilutions to weaken it by orders of magnitude. It would be pretty stupid though.

>> No.9669353 [DELETED] 

I’m doing self-study by working all the way through 3 textbooks, one at a time. I’m halfway through calculus, so should I do linear algebra or differential equations next? I know enough DE to cover maybe a bit less than a quarter of the book I have, but absolutely no experience with linear algebra.

>> No.9669361

I’m doing self-study by working all the way through 3 textbooks, one at a time. I’m halfway through calculus, so should I do linear algebra or differential equations next? I know enough DE to cover maybe a bit less than a quarter of the book I have, but absolutely no experience with linear algebra.

>> No.9669371

>>9669255
I don’t know how to specifically define the model, but
https://www.quora.com/Why-dont-flies-die-when-you-punch-them
I’m assuming how exactly you should convey the information in the link is spelled out in your textbook.

>> No.9669380

>>9656198
Do you think I can get away with taking linear algebra and algebraic geometry in the same semester? Not asking for the sake of overlap because I know nothing, asking only in the context of workload.

>> No.9669404

>>9669361
If you're going from calc, diffy q would make more sense. But that's just my experience.

>> No.9669411

>>9669303
> what's the point of rolling steel?
Making bars/plates of a specific thickness. Steel is initially poured in very thick slabs, much thicker than is useful for anything, then squeezed through rollers to reduce the thickness to something more useful.

> I'm talking about what are those rolls of steel used for? They look so impractical, how are they used to build things?
That's how large quantities of thin sheet steel (e.g. for car body panels) are transported. Steel is pulled off the roll then cut and pressed into shape. A continuous roll is more convenient than discrete sheets.

>> No.9669422

>>9669380
>Do you think I can get away with taking linear algebra and algebraic geometry in the same semester? Not asking for the sake of overlap because I know nothing, asking only in the context of workload.
In the context of workload yes, but if you don't know linear algebra you probably don't know enough algebra to take algebraic geometry

>> No.9669436
File: 14 KB, 560x420, 1519137769431.jpg [View same] [iqdb] [saucenao] [google]
9669436

Im trying to solve this by using Newton's method but i keep getting the same root (~ -15) regardless of which starting point i choose. I want a value for the second root thats ~20. Is there any way i can simplify/change my function or should i just use another algorithm?

>> No.9669502

>>9669436
I really doubt this suggestion will fix the problem for this case but if you wrote the algorithm, try making a test to detect when [math]f'(x_i)[/math] is close to zero, and if it is then tell the program to modify the Newton-Raphson equation by substituting the [math]\frac{f(x_i)}{f'(x_i)}[/math] term with [math]\sqrt{\frac{-2f(x_i)}{f''(x_i)}}[/math].

>> No.9669593

You know how heat rises? How do calculate it?

I'm specifically dealing with a 0.02m^2 hole at 500'C. The only inlet is velocity +0.05m/s, the actual number will be more than this though, how can I calculate the actual velocity?

>> No.9669610

anybody know a good textbook to go over capacitance, magnetostatics, and transmission lines? I have a midterm tomorrow, but I need more resource material to learn this.

>> No.9669615

>>9669361
>I’m doing self-study by working all the way through 3 textbooks, one at a time. I’m halfway through calculus, so should I do linear algebra or differential equations next? I know enough DE to cover maybe a bit less than a quarter of the book I have, but absolutely no experience with linear algebra.

linear algebra's super important for almost any field you go into, so honestly i'd recommend you get started on that. It's also important for multivariable calculus, so these things loop around, see

>> No.9669662
File: 7 KB, 609x61, analy.png [View same] [iqdb] [saucenao] [google]
9669662

How do you prove that the LUB/supremum of this set is equal to m?

>> No.9669675

>>9669662
What have you tried?

>> No.9669691
File: 38 KB, 475x273, Board to Board Connectors.jpg [View same] [iqdb] [saucenao] [google]
9669691

>>9656198
mech e here

i want to know about current and magnetism in complicated metal structures. looking at a circuit diagram is one thing.. those are much simplier, but why doesn't current flow through an entire structure?

i can understand wires, they're just an insulated strand/strands of wire. but what about pcbs and other electronics/signal carrying devices? how can some of them be made of metal but still carry a distinguishable signal? hopefully this makes sense.

>> No.9669720

>>9669675
I think I'm trying to say that the LUB = c,

and that c^2 = m,

because if c^2 > m, then there is some "space" between c^2 and m, so because the reals are dense, there is some number r such that c^2 > r > m. I'm struggling to go from here though, essentially showing that (c-r)^2 is also greater than m, therefore c was never the real LUB (contradiction)

I'd imagine a similar proof for the case where c^2 < m.


I can't put this into mathematical terms though.

>> No.9669775

>>9669422
Are we talking real linear algebra or the bullshit intro linear algebra (basically only computations) that everyone takes and calls it linear algebra. Also at my university one isn't a prereq for the other. I can't take analysis due to some timing error but I would like to take linear algebra and another math class that semester. I was between algebraic geometry, intro topology, and a higher level course in either ordinary or partial differential equations.

>> No.9669776

>>9669615
how much linear should you grind
i already took meme american lower div linear but that class was so free it's not even a real class.
should i autism out every problem in shilov?

>> No.9669790

>>9669775
>Are we talking real linear algebra or the bullshit intro linear algebra (basically only computations) that everyone takes and calls it linear algebra.
The distinction isn't really relevant since you don't need much actual knowledge of linear algebra for (introductory) algebraic geometry but if you don't know it at all it's just a sign that you likely won't be prepared for algebraic geometry, even if the algebraic geometry is specifically made to be very low-level and self-contained

>> No.9670037

Do black holes evaporate due to annihilation?

>> No.9670038

>>9669662
It's actually (and quite obviously) sqrt(m). Counterexample to your claim that it is m: m=0.25 + epsilon. Then 0.5 is an element of L

>> No.9670056

>>9669662
there's no supremum

>> No.9670069

>>9670056
Ya there is - the set is non-empty and it is bounded by m + 1

>> No.9670074

How do I get back into studying when my brain is over-saturated in dopamine from constant stimulation from video games and internet content?

>> No.9670076

>>9670074
try flogging yourself every time you get distracted

>> No.9670078

How do I know if I'm really smart? I feel very strong is some fields, but yet in some others like geography, math and history I'm bad af. Are IQ tests legit for this? And is there a good free IQ test?

>> No.9670084

>>9667141
>>9667154
"Invert this function" and "restrict the domain of this function to make it invertible" are two totally different tasks. For a function to be invertible it has to be bijective. The domain of the function are the inputs. As you can see on your plot, for all x > 0, f(x) =1, and for all x < 0, f(x) = -1, so how do you have to restrict x such that you can get back the original x from f(x)?

>> No.9670086

>>9670069
>the set is non-empty
Only for m > 0

>> No.9670096

>>9670086
shoot you're right - I cut off the part that said m is a positive real, my bad

>> No.9670100

>>9669662
>>9669720
prove that there are no real numbers between x and sqrt(m) that is NOT an element of L

>> No.9670101

>>9670078
>Really smart
Be great at math.

>Smart
Type with proper grammar and punctuation.

How easily you can make people laugh is also positively correlated with intelligence. Being “the funny one” usually also means you’re the smart one - unless you’re a girl, of course. This applies even to autists and agoraphobes.
The American SAT is also a good measure; studying really only gives you an advantage of a hundred-or-so points afaik. The people with perfect scores are exclusively geniuses.
Don’t try to measure your IQ. Online tests can’t be trusted, and you will gain nothing by seeing the exact number.

>> No.9670102

>>9669662
What level of math is this? Is it high school calculus? genuinely asking from any anon who knows

>> No.9670107

>>9670102
I’m not sure but it’s not anything you learn in high school or first-year college. There are no infinitesimals, so it’s not calculus. Maybe linear algebra or set theory?
I actually don’t even know if “set theory” counts as a guess.

>> No.9670108

>>9670107
>>9670102
it's real analysis

>> No.9670115

>>9670108
is it from papa rudin/is this introductory?

>> No.9670126

>>9670101
I don't see the math happening, but propper grammar and punctuation I can do. Thanks for the insight.

>> No.9670130

>>9656439
you dont know how to study for math class

>> No.9670136 [DELETED] 

>>9669720
L⊂R :={x|x>0 and x<sqrt(m)} = L⊂R+{x|x<sqrt(m)}

R+\L := {x | x ≥ sqrt(m)}.

Let c ∈ R\L and c < sqrt(m) (In other words, c is not included in L but is less than sqrt(m))

c ∈ R\L → c ≥ sqrt(m) (contradicts c < sqrt(m))

q.e.d.

>> No.9670140

>>9669720
L⊂R :={x|x>0 and x<sqrt(m)} = L⊂R+{x|x<sqrt(m)}

R+\L := {x | x ≥ sqrt(m)}.

Let c ∈ R+\L and c < sqrt(m) (In other words, c is not included in L⊂R+but is less than sqrt(m))

c ∈ R+\L → c ≥ sqrt(m) (contradicts c < sqrt(m))

q.e.d.

>> No.9670153
File: 2 KB, 564x72, sum.png [View same] [iqdb] [saucenao] [google]
9670153

what is the formula to solve this kind of equations?

>> No.9670155

>>9668948
do 5 minute studying sessions, than 6 minutes. than 7, focus is a skill you can train, like any other.
pysch wise: do I check in/check out and figure out how you feel before the 5 minute and after and figure out what your hang up/fear is. This part is very hard to do solo for young people though

>> No.9670174

>>9670153
what lvl of math? There are algebra hand worked formulas for all degrees up to 6 that were used in math contests in the 16th hundards, but no one actually uses them today past quadratic formula. Also Fundamental theorem of algebra.

>> No.9670189

>>9670153
I don't think there is a general formula yet

>> No.9670194

>>9670140
This makes sense to me but I'm confused overall what it's proving. Aren't we trying to prove that c (the supremum) is equal to the square root of m? Maybe I'm not understanding.

>> No.9670197

>>9670194
It's proving that m is equal the supremum of L by showing that there's nothing between m and and the supremum of L

>> No.9670203

>>9670197
Oh wait, it proves that sqrt(m) is the supremum ,not m

>> No.9670208
File: 14 KB, 327x499, 31T1cw7-f4L._SX325_BO1,204,203,200_.jpg [View same] [iqdb] [saucenao] [google]
9670208

>>9670153
Abel–Ruffini theorem says there isnt, algebraically... but
http://m-hikari.com/ams/ams-2015/ams-93-96-2015/p/kamyshlovAMS93-96-2015.pdf
https://www.gaussianwaves.com/2014/02/polynomials-convolution-and-toeplitz-matrices-connecting-the-dots/
also there is a lot of information you can find out, if you need aporamations

>> No.9670237

>>9670208
"Beyond the Quadratic Equation"

sounds like some epic fantasy novel bullshit
love it

>> No.9670255

>>9670237
actually it is "beyond the quartic..." not Quadratic, just in case that wasnt a typo.

>> No.9670266

>>9670153
There are general closed-form solutions up to quartic (x^4). There is not (indeed, cannot be) a general closed-form solution for quintics and above. If you need to find the roots, you do so numerically.

But note that the problem is ill-conditioned for high-degree polynomials. Very small changes in the coefficients can result in large changes in the roots. See e.g. the article for "Wilkinson's polynomial" on wikipedia.

>> No.9670272

>>9670266
>There is not (indeed, cannot be) a general closed-form solution for quintics and above.
You need to add the term "algebraic" here, or else this is false.

>> No.9670284

>>9657519
probably this

>> No.9670290

>>9670272
what is then the non algebraic solution for quintics and above?

>> No.9670293

>>9670290
https://en.wikipedia.org/wiki/Bring_radical#Solution_of_the_general_quintic

>> No.9670295
File: 18 KB, 1012x794, Untitled.png [View same] [iqdb] [saucenao] [google]
9670295

How is F' = F cos(theta)?

>> No.9670300

Brainlet here.

So these mathematical models scientists and engineers use... are these equations just created on fly to describe something or are these equations that are long-known to be associated with a certain problem?

Like, there is a mathematical model for predicting lean angles, traction limits, velocity for motorcycles (or any single track vehicle, bicycles) making a turn. Did somebody sit and 'invent' this equation or is this something that is intuitively known?

>> No.9670302

>>9658801
>recession
the government definition is two consecutive quarters of negative economic growth as measured by a country's gross domestic product (GDP).
But it is a pretty useless definition, mostly because using GDP to measure economic health is turning out to be pretty retarded in the modern economy.

>> No.9670307

>>9670295
is f a ray?

>> No.9670309

>>9670295
Not sure what F’ is or what the arrows mean, but:
Cos(theta) = adjacent/hypotenuse
F = adjacent
I’ = hypotenuse
I’cos(theta) = adjacent(hypotenuse/hypotenuse) = adjacent = F

>> No.9670312
File: 32 KB, 776x731, cut.png [View same] [iqdb] [saucenao] [google]
9670312

>>9670307
Here's the original formulation.

>> No.9670322
File: 75 KB, 1024x962, 1496445060894.jpg [View same] [iqdb] [saucenao] [google]
9670322

>>9669502
thanks for the suggestion but it didn't really work. I also tried using Halley's method and then i tried Secant method but it still converges to the same root. I think i might just have to use Bisection. This shouldn't be this hard :(

>> No.9670335
File: 56 KB, 1000x800, 1522205774237.jpg [View same] [iqdb] [saucenao] [google]
9670335

>>9669502
>>9670322
Shieeeeet Secant actually worked, im retarded

>> No.9670416
File: 667 B, 144x94, 1509956772511.png [View same] [iqdb] [saucenao] [google]
9670416

Length of the tree's shadow is 10.2m, whereas length of the human's shadow is 2.5m, and his height is 1.7m. Fin the height if the tree.

This is retarded, how can a human cast shadow if it stands inside tree's shadow? Fucking hate this kind of shit.

>> No.9670468
File: 2.46 MB, 4032x3024, 733F40EE-C3D6-481C-840D-9F740642A5A7.jpg [View same] [iqdb] [saucenao] [google]
9670468

>>9670416
Trees don’t make solid shadows like humans.

>> No.9670474
File: 2.52 MB, 4032x3024, 0981F937-5F20-48E4-8681-7FB261DB6B9B.jpg [View same] [iqdb] [saucenao] [google]
9670474

Why do they want me to replace y with u? It gives the same result either way. Feels kinda like they’re intentionally fucking with me.

>> No.9670493

>>9670468
I've solved it beforehand, but it is fucking retarded do not specify if human's shadow inside the tree's shadow or added to it at the end.

>> No.9670533

>>9670493
I'm pretty sure you'd get the same answer if you tried it that way.

>> No.9670548

What equipment would be needed to harvest minerals from asteroids?

Also, what could be done to change an asteroid's trajectory?

>> No.9670584

>>9670533
nope, it would be different

>> No.9670588

>>9670548
wasn't Armageddonwith Bruce Willis about that? I think they tried to change it using potent nuclear bomb planted inside - to split and change direction of the leftovers

>> No.9670593

>>9670153
https://en.wikipedia.org/wiki/Niels_Henrik_Abel#Contributions_to_mathematics

>> No.9670602

>>9670300
>Did somebody sit and 'invent' this equation
Yep, Isaac Newton. He came up with most of what you're talking about when he invented calculus. The basic physics also evolved directly from his work, which makes sense considering he created the math to solve a physics problem. For whatever reason, discoveries in mathematics tend to lead to advancements in science.

An engineer was almost definitely the one to come up with the form and values associated specifically with the model for motorcycles, but broader concepts like traction and velocity come straight from classical physics, most of which was developed alongside calculus.

>> No.9670605

Is it incorrect to define i is equal to the square root of -1?
My professor says that i^2=-1 is the only valid definition, but Wolfram defines it as the square root of -1 http://mathworld.wolfram.com/i.html

>> No.9670608

>>9670605
Is it incorrect to state that i is defined as the square root of -1*

>> No.9670616

>>9670584
Why?

>> No.9670624

>>9670605
Your professor is technically correct but he's also a dick. They mean the same thing.

>> No.9670626

>>9670605
Definition and use aren't the same thing.
Your professor is correct, but it doesn't really change much. Just watch your bounds.

>> No.9670637

>>9670616
because
use similarity proportion to solve it and you will see

>> No.9670746
File: 14 KB, 846x107, 1521935189309.png [View same] [iqdb] [saucenao] [google]
9670746

what is the rational way to solve shit like that?
I've just deconstructed (3^32-2^32), another solution I saw multiplied both parts by 5 to get rid of 0,2. This make sense, ofc, but then it proceeds to transform 5 into (3^2-2^2).
I have no issues understanding why is that so but is there some kind of forumla for that or something? Because imagine it wasnt 5 but 2345326546324623 - you cant just transform it into sum of quadrats or whatever easily.

>> No.9670755

>>9669790
Oh I was asking because I have taken some linear algebra I just haven't taken what I thought most would consider "real linear algebra" I know the fundamentals like basis span dependence and independece eigenvalues and eigenvectors orthogonal sets and orthogonal matrices diagonalization and I also learned about eigenfunctions in diff eq. Do you think that's sufficient? Or would I be better off taking a class in topology or higher order ODEs or higher order PDEs

>> No.9670843

>>9670755
Have you taken any other algebra (rings, fields, groups,...)? I would suggest topology before algebraic geometry anyway, and moreso suggest speaking to one of your professors about this

>> No.9671188

>>9670203
>>9670197
this seems like circular reasoning? How does it prove that nothing is between the supremum and sqrt(m)?

>> No.9671218

>>9671188
If sqrt(m) is indeed the supremum of L, that would mean that there exists a real number less than sqrt(m) that is NOT an element of L. sqrt(m) is proven to be the supremum of L by showing that it's impossible to have a real number that's less than sqrt(m) but is not included in L.

In the shitty proof, saying that c ∈ R+(the in-between number) is less than sqrt(m) and is not included in L makes a contradiction since the condition for it to not be included in L is for it to be greater than or equal to sqrt(m)

>> No.9671227

>>9670295
>>9670312
h-help

>> No.9671233

>>9671218
>If sqrt(m) is indeed the supremum of L, that would mean that there exists a real number less than sqrt(m) that is NOT an element of L

Do you mean if sqrt(m) isn't the supremum of L? Doesn't supremum mean that it's the least upper bound, so real numbers below it should be included in L?

>> No.9671256

>>9671233
>Do you mean if sqrt(m) isn't the supremum of L?
It's an assumption

>Doesn't supremum mean that it's the least upper bound, so real numbers below it should be included in L?
yes, that's why it leads into a contradiction

>> No.9671283

>>9671227
Could you post something that's a little more informative than your first pic, and less abstruse than the second?

>> No.9671479

is (1/|z|) = z ???

>> No.9671490

>>9671479
http://www.wolframalpha.com/input/?i=1%2F%7Cz%7C

No...?

>> No.9671503

>>9671490
i meant 1/|z|=|z|
I copyed this from class and makes no sense

>> No.9671507

>>9671503

counter example:
z = -4

>> No.9671518

>>9671507
true. What could it be then?
actuallyit says something like |z^-1|=|z|

>> No.9671526

>>9670843
Would you recommend topology over a class in ODEs or PDEs? That's what I'm between if algebraic geometry is out since I don't have a very rich algebra background.

>> No.9671530
File: 447 B, 89x20, dem13.png [View same] [iqdb] [saucenao] [google]
9671530

>>9671507>>9671518

Probably it was this

>> No.9671535

>>9671503
only if z = ±1

>> No.9671541

>>9671535
yeah, but i think it was >>9671530

>> No.9671553

>>9671541
Write them both as fractions, then determine whether or not the absolute value sign can be manipulated such that both sides of the equation are the same.

>> No.9671569

>>9671530
>>9671479
1/a = a^-1
|a| = sqrt(a^2)

1/|z| =1/sqrt(z^2

|1/z| = sqrt((1/z)^2)
= sqrt(1/z^2)
= sqrt(1)/sqrt(z^2)
=1/sqrt(z^2)

∴|1/z| = 1/|z|

>> No.9671953

>>9670746
a^2-b^2 = (a+b)(a-b)
=> 3^32-2^32
=(3^16+2^16)(3^16-2^16)
=(3^16+2^16)(3^8+2^8)(3^8-2^8)
=(3^16+2^16)(3^8+2^8)(3^4+2^4)(3^4-2^4)
=(3^16+2^16)(3^8+2^8)(3^4+2^4)(3^2+2^2)(3^2-2^2)
=(3^16+2^16)(3^8+2^8)(3^4+2^4)(3^2+2^2)(3+2)(3-2)
=(3^16+2^16)(3^8+2^8)(3^4+2^4)(3^2+2^2)*5*1
(3+2=5, 3-2=1)
=> (3^32-2^32)/5 = (3^16+2^16)(3^8+2^8)(3^4+2^4)(3^2+2^2)
IOW, they aren't "transforming" 5 into (3^2-2^2), they're just leaving (3^2-2^2) (or 3+2) alone, rather than reducing it to 5.

But any composite number n which is either odd or a multiple of 4 can be expressed as the difference of squares. If n=x*y, put
x=a+b
y=a-b
=> a=(x+y)/2
=> b=(x-y)/2
=> n=x*y=(a+b)(a-b)=a^2-b^2
If n is odd, then x and y are both odd so x+y and x-y are both even so a and b are integers. If n is a multiple of 4 then it can be factored so that x and y are both even so x+y and x-y are both even so again a and b are both integers.

The only case where n can't be expressed as a difference of squares is if it's prime or if its prime factorisation has an odd power of two (x and y will inevitably have different parities so a and b will be non-integral).

>> No.9671962

>>9671953
>>9670746
> Because imagine it wasnt 5 but 2345326546324623 - you cant just transform it into sum of quadrats or whatever easily.
2345326546324623 = 547116641 * 4286703
= (275701672+271414969)*(275701672-271414969)
= 275701672^2-271414969^2
The hard(est) part is factoring (3*17*84053*547116641).

>> No.9672224

Here's the situation; you own a store and on average 10 people come into your store per hour. Once a customer is in the store they immediately start browsing your products, and it's found that they have a 0.8 probability of buying that product. This means we can assume the compliment; that they have a 0.2 probability to NOT buy that product - this means they put down the first product, pick up a second product and repeat the whole process. We can also assume that everyone who enters the store is going to eventually but a product, customers are independent, product browsing is independent, and any other naive assumptions for the sake of simplicity.

The first part, how many people enter the store, can pretty obviously be simulated through a random draw from a poisson distribution where lambda = 10; simple enough. However, for the next part we define "b(sub)i" as the amount of books that customer i would browse before making a purchase. For example, when b(sub)i = 0 the customer purchased the first book they picked up. When b(sub)i = 2 the customer browsed TWO (2) products before making a purchase on their third.

What would the distribution of b(sub)i be?

My thinking it is maybe Bernoulli distributed because the decision to browse again or buy is 0.2 & 0.8 respectively; a weighted coin flip. However, in most cases there will be multiple of these Bernoulli trials which then makes the case of it being Binomially distributed - but it's impossible to tell how many trials (N in Binomial) because that depends on the outcome of the previous trial.

Maybe the N is the amount of products in the store, because you theoretically could browse every product. Then we define X as the number of times the customer browses, meaning it can take on any value [0, N]. And then if we say that browsing a book is a success then the probability of success is 0.2.

Am I seriously just overthinking this? Is it Bernoulli, is it Binomial, is it something completely different?

>> No.9672232
File: 40 KB, 834x512, Screen Shot 2018-04-15 at 10.45.29 am.png [View same] [iqdb] [saucenao] [google]
9672232

>>9672224
If it helps I simulated the whole situation.

After "running the store" for 1000 hours this is a histogram of the number of products browsed for each customer [ b(sub)i ] over the 1000 hours of the store being open.

Does this jump out as being any sort of obvious distribution? I can calculate proportions if need be instead of just their frequency.