/sqt/ - Stupid Questions Thread

yo what is this board for

>>8283685
Science & Math

Though engineering has its own board >>>/hm/ if youre interested

Say you invent something /sci/ related and useful who the actual fuck do you talk to about it (other than /sci/) if you are outside academia and have no connections.

>>8283691
Venture Capitalists could be an option i guess

>>8283691
Patent office.

Reposting: Next week I'm starting the last school year of my bioinformatics undergrad and I'm thinking about doing a masters in math with some relevance to bioinformatics. The reason being that I don't want to be an analytical bioinformatician/computational biologist but an actual bioinformtacian working on interesting algorithms. Any advice on what subjects to take? Maybe I should do a masters on systems biology?

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How come 4 * (c/a) became 4ac here?

since 0.999... = 1, does that mean that 0.999... is a prime number as well?

>>8284404
1 is not a prime number, so no.

>>8283683
How do you obtain 6,42 with three numbers you can multiply or add between themselves?
I know 1+2+3=6 and 1*2*3=6 but 6,42?

I have been seeing some symbols recently.

What does the upside down A mean? It's like a V that has been stroke through by an horizontal line.

Also, what does a '.' mean? It's basically three points forming an upside down triforce. I know the upside down of this upside down means "therefore"?

>>8284345
Multiply top and bottom by [math]a[/math].

>>8284473
What does this even mean?
[math]6,42 + 0 + 0 = 6,42[/math]

>>8284489
But 6,42 * 0 * 0 = 0 and not 6,42

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Can someone walk me through this I feel like a fucking retard. The farthest I got was tan^2(x)+tan(x)=1 but I still can't figure out how to get x.

Sleep deprivation definitely has a hand in this but I wont be able to sleep until I figure this out.

>>8284491
Oh. If that's what you meant, then just set [math]a + b + c = d[/math] and [math]abc = d[/math] and use Vieta because they are symmetric sums.

>>8284494
You can solve it like a quadratic. Because it *is* a quadratic.

>>8284494
sec + 2 = 2sec + tan
2 = sec + tan
2 = tan^2 x + tan x + 1
tan^2 x + tan x - 1 = 0

That is a quadratic that you can solve for tan x and then get the inverse tan of that to get x

>>8284480
The upside-down A means "for all." It's should be accompanied by some variable, like x. So you would see [math]\forall{x}\in{S}[/math] ... followed by some proposition. It would be read "for all x in [some set] S, such-and-such is true."

You may also see a backwards E, which is similar and means "there exists (at least one)..."

The second symbol just means "therefore."

Any good intro book on logic or proofs should go over this stuff. It's useful to know.

>>8284517
Sorry, the second symbol means "because..." not "therefore." Didn't read

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>>8284505
>>8284501
>quadratic
holy shit I really am retarded. Didn't even consider that, thanks niggas.

>>8284499
I'm too retarded to understand how to use it. Care to explain?

Medical question for a medical novel idea, could a single surgeon with the best training and equipment perform a organ transplant single handedly and if not what's the bare minimum of people needed?

>>8283683
So I'm trying to derive the Kline-Gordon equation from the action, taking [math] \mathcal { L } = - \frac { 1 } { 2 } \left (\partial ^{\mu} \varphi \partial _{\mu} \varphi + m^2 \varphi ^2 + 2 \Omega \right )[/math]. Then [eqn] \delta \mathcal { S } = - \frac { 1 } { 2 } \int \operatorname { d } ^4 x \left ( \partial ^{ \mu } \delta \varphi \partial _{ \mu } \varphi + \partial ^{ \mu } \varphi \partial _{ \mu } \delta \varphi + 2 m^2 \varphi \delta \varphi \right )= 0[/eqn] Now I'm not quite sure where to go from here, I've read that you perform integration by parts on the first two terms (and require that the [math] \delta \varphi [/math] vanish at infinity to remove the boundary terms), but I don't know how to do parts on an integrand like this. Anyone have any tips and general pointers?

Is it possible in our lifetime that we will see reverse aging?

>>8284487
Wouldn't it require to multiply every place to a instead of a single factor?

>>8284565
No. If you multiply one factor by a/a, then you're multiplying by a form of 1, which is valid.

>>8284595
Thanks.

>>8284532
You want to use IBP to reduce the terms proportional to the derivative of delta phi to being proportional to only delta phi.

Then the integrand is proportional to delta phi, which gives you the differential equation.

>>8283683
How much Calculus do I have to know before I can start working my way through a physics textbook?

>>8284651
Depends. But really you know up to vector calculus, but you'll be able to read some introductory books with just single variable calculus.

>>8284487
Multplying top and bottom by a would give 4ac/a^2 and not 4ac.

How practical is chemistry as a career really? Ive always been told that it was a wonderful career choice and its always been my dream to go to graduate school and get my PhD but im starting to have second thoughts. Ive been doing research work for two years and have a few minor publications with a major one coming within the year and yet the professor I work with makes about $65k a year and he doesnt seem all that happy with how things have turned out for him. The mans a complete genius, got his PhD in 2 years in Germany before moving to the US to teach and it seems as if ill never be on his level of pure knowledge when it comes to the field. If even he didnt make it big when he seemed to be a golden boy in school im starting to believe that I shouldnt go through all that schooling only to end up in a position doing grunt work or teaching entry level classes for 1/3 less pay than someone with far less education and training.

I know its anecdotal evidence but im starting to think if I should just give up and go into medical school or just be a retail pharmacist like my dad.

>>8284685
Why don't you just do what you enjoy?

>>8284696
People can enjoy several different things, so unless you are some sort of autistic monomaniacal retard, it is logical to consider which of your interests will be a more feasible career.

>>8284543

No.

>>8284345
>>8284666
Yeah it looks like a mistake...

[eqn]-\frac{b}{2a}\pm\sqrt{\left(\frac{b}{2a}\right)^2-4\frac{c}{a}}=-\frac{b}{2a}\pm\sqrt{\frac{b^2}{4a^2}-\frac{4c}{a}}=-\frac{b}{2a}\pm\sqrt{\frac{b^2-16ac}{4a^2}}[/eqn]

I'm guessing it should be

[eqn]-\frac{b}{2a}\pm\sqrt{\left(\frac{b}{2a}\right)^2-\frac{c}{a}}=-\frac{b}{2a}\pm\sqrt{\frac{b^2}{4a^2}-\frac{c}{a}}=-\frac{b}{2a}\pm\sqrt{\frac{b^2-4ac}{4a^2}}[/eqn]

>>8284696
because I believe in being pragmatic and being surrounded by professors far smarter than I will ever be who dont seem to be all that thrilled with where they are today its making me lose faith that this is the right choice for me. Im far from being in it for the money but im still seeing a top 20 globally ranked school graduate with 15 years of experience work 60 hours a week teaching dumbshit undergrads all while trying to produce publications and having to jump through all the hoops that being a professor at a public university entails only to end up under appreciated and underpaid.

I love chemistry I really do but im starting to think more and more about just taking the easy route.

>>8284704
>im starting to think if I should just give up and go into medical school or just be a retail pharmacist like my dad.
These don't sound like the words of a person who would seriously enjoy the other options available.

>>8284696
I enjoy painting but I sure as shit wouldnt consider making it a career

>>8284721
Why not do research in industry? There's probably some cool shit out there.

>>8284728
That has always been my goal which is why I posted in this thread in the first place to see if anyone actually had any experience in the field. Im surrounded by academics both at work and in class so I havnt got to speak with many people on the industrial side of things.

Tourist here.

What are effective theories exactly?
Universe Review (from sticky) describes them as theories with unmeasured parameters, while Wikipedia describes them as '[...] theor[ies which] proposes to model a certain effect, without proposing to adequately model any of the causes which contribute to the effect.'

Can /sci/ clarify?

>>8284758
From what I remember, effective theories are those that have been proposed based off already existing theories but are still being tested. Take, for example, theories based off the Standard model such as string theory.

>>8284719
Yeah, that would be right. It's supposed to be (p/2)^2-q, with p = b/a and q = c/a.

>>8284602
Not exactly helpful desu.

Going through Rudin. In his discussion of the Cantor Set, he states
>No segment of the form [math]\left(\frac{3k +1}{3^m}, \frac{3k +2}{3^m}\right)[/math], where k and m are positive integers, has a point in common with the Cantor set.
Can someone explain why this is the case?

Why do scientists use Latin (in vito, ab inito) in publications? Who started this pretentious trend?

>>8284874
The same people that started science itself. You will also find a lot of greek and some arabic terms.

>>8284758
That term has a specific technical meaning in quantum field theory. Is that what you're asking about?

what are the best books for proves, topology and calculus? (and why)

>>8285079
you sound like you don't know what you're doing at all. why do you want to learn topology with calculus? that's called analysis. if you want analysis, go for Terence Tao's Analysis I.

Is there any (micro)biology branch that requires heavy math knowledge?

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Do light years have a leap year every 4th light year?

>>8285105
kek

(It is based on the Julian year, for everybody actually wondering)

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I found this in a textbook that was recommended to me. I don't understand, shouldn't 0/0 be undefined? Why does the book allow me to do it?

>>8285102
No. Biology is for brainlets.

>>8285100
(I didn't know Tao wrote textbooks...)

>>8285102
Systems biology

>>8285122
0 | a is the same as saying a = 0x for some x. So a must be 0. It's just saying that if 0 is only ever a factor of 0.

>>8285137
It's just saying that 0 is only ever a factor of 0. *

>>8285131
But playing God with some micro-faggots sounds fun as fuck.

>>8285100
one book for proves
another book for topology
and a third book for calculus

>>8285137
>>8285138
I overlooked that. Does that mean that the operation itself is possible, but that 0/0 doesn't have a defined outcome?

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Here with another retarded geometry question.

DE // AB, AF and BF are bisectors of the angle A and B respectively, AC = 8 and BC = 12.
How do I find the perimeter of triangle DEC?
I'm starting to get a little frustrated. I've tried with a lot of theorems, including Thales and a lot of weird proportions. I think it can be solved with a system of equations, but still can't figure out which one.
A hint or the solution would be greatly appreciated.

>>8285156
In a way, yes. Because, in the example a = 0x, the factor x can be anything, x = a/0 = 0/0 is considered undefined. Otherwise, we could replace 0/0 with whatever number we want whenever we encounter it, and we would pretty much break mathematics.

Just remember that the statement "0 | a" is just a statement that is true or false - "0 is one of the factors of a" - unlike the statement "0 / a" which is an actual numerical value.

How can I understand maxwell's equations beyond just knowing the formulae

An intuitive sense, how

The only thing I know is there are no magnetic monololes, which i only know because i remember that phrase. I don't know why specifically that it is so..

>>8285224
>magnetic monololes

>monololes

You might wanna keep reading.

>>8284939
No, I don't think so. I stumbled upon this term in Introduction of http://universe-review.ca/F01-introduction.htm#evolution, so I don't think author had quantum field theory.

>>8284939
>>8285235
*in mind.

>>8285231
Phone posting in suffering

>>8285224
There's a book called Electrodynamics by Fulvio Melia that starts with the derivation of maxwells equations from physical observables. I think it's pretty well done.

>>8283683
I study neuroscience. Applying to a masters program next year in cog/neuro.
Should I learn html/css/javascript etc? or just go into C and such?
I have the fundamentals down, as I studied CS for a year.

ive read that psychologists use python and some proprietary languages to develop tests and automate results, I just want to know what you guys think.

just a reminder, this is a stupid questions thread

If my universe is all Real numbers, and I'm referring to ALL Integers (not all Reals), would I say:

(∀x)(x is an integer)
OR
(∃x)(x is an integer)

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I was watching Meme Academy, and I witnessed Sal derive a kinematic formula, [math]\vec{s}=\vec{v_o} \Delta t+\frac{1}{2}\vec{a}\Delta t^2[/math] . I mean, it's all cool and shit, pretty simple, easy, but how the fuck could I ever derive this on my own, without even knowing what to use as a substitution instead of something in the equation?

Is this one of those formulas, that you just learn to derive by heart, just because x is something that must absolutely be substituted by (y+z), even though it could be also substituted by 2(p+q), but if we did that, it wouldn't work?

Like, how the fuck do I learn what to substitute for what to derive my formulas? There must be a logical solution to this, right?

>>8285484
[eqn]\forall{x}\in\mathbb{Z}[/eqn]

>>8284424
REKT

>>8285542
Thanks. So I'm allowed to use ∀ to refer to any other universe or just a sub-set of the universe I'm using?

>>8285538
Things like this crop up all the time. Oftentimes the derivation of a formula involves a trick or two that you would never have thought of. That's because it's all built on knowledge that's been developed for centuries or decades by a few clever people.

So the best thing you can really do is make the most sense of it that you can. Remember the general gist of it, as well as whatever specific trick there is.

Anyway, you shouldn't expect to remember how to derives the kinetic formulas. Just get the gist of their derivations, then remember them and use them. It's like how you remember how to add and subtract, but you don't count on your fingers each time. It's just natural, and there are bigger things you should be worrying about.

>>8285558
Yes, you can use it for any set; doesn't have to be limited to the universe. What I wrote is read "for all integers x..." and limits the discussion to the integers. It's all very flexible.

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why exactly can i do that? what exactly am i doing here? is there a related proof?

"gesamtheit" = all
"vollständig" = complete (? ì guess)
"zulässig" = allowed
"entwicklung" = expansion

This seems like a pretty big step and all of it got left out..

I need to find the limit of x as x approaches infinity

The equation is -(3x^2)/(4x+4)

Is the answer to this -1?

>>8285588
The entirety of the "eigenfunction" (seems like everybody uses the german term?) of a hermetian operator is complete in the following sense:
Every (allowed) function x can be represented as a development according to the orthonormal eigenfunctions

>>8285599
Nope.

[eqn]\lim_{x\to\infty}\frac{-3x^2}{4x+4}=\frac{-\infty}{\infty}[/eqn]

Use L'Hopital's rule:
[eqn]\lim_{x\to\infty}\frac{-6x}{4}=-\infty[/eqn]

>>8285613
Is not (-infinity/infinity) = -1?

Also, I'm beginning my Calc 1 course and this is from a pre-calc review homework sheet. I haven't learned L'Hopital's rule

>>8285622
no, read indeterminate forms, L'Hospital's rule, etc.
Infinity isn't a number and doesn't follow algebraic relations defined on the real numbers. ESPECIALLY at the level of intro calc, remember something like 'infinity' is sloppy for 'the limit of this expression as x approaches [value] is unbounded from above.' An infinite limit can be useful in terms of notation to denote whether it diverges off to a positive value or negative value, or if it just oscillates wildy or becomes a discrete jump such that the limit doesn't exist.

>>8285588
Just an addition to >>8285609 , you take the eigenfunctions to span your function space. If you're not familiar with complete sequences of a function space--which is really the business of functional analysis where you start to get picky about the technicalities--think of it like a Fourier series expansion of a function. The sines/cosines make up the basis (function) vectors and the coefficients define the function. Same thing for an eigenvector (function) decomposition of a general function in QM.

>>8285622
That's a good thought, but you can't "divide out" infinity like that. Basically because infinity in this context isn't actually a number per se, but representing an *approach* toward infinity.

[math]\frac{-\infty}{\infty}[/math] is one of many "indeterminate forms" and you'll learn more about this and L'Hopital's rule in Calc 1.

For now, I'm guessing they just want you to say that the limit is undefined. How is the problem stated?

>>8285559
Damn, that's depressing.

>>8285645
>>8285646
I realized I couldn't divide infinity like that, so I looked up indeterminate forms and I understand it a bit. This is how I approached the problem. Can you tell me if this is correct?

I circumvented the problem by dividing each term out by x, which reduced the problem to -(3x)/(4+4/x) which I reduced to -infinity/4

Which the answer to that is -infinity. Did I do this right?

>>8285645
>think of it like a Fourier series expansion of a function
this is pretty much how i thought of it - i just don't see the point that you can present for ANY problem a solution in the form of fourier or orthonormal eigenfunctions or w/e is still out there without me knowing about it

>>8285668
Yes that's correct.

Remember that technique, by the way. It comes up a few times.

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Is there a way to have a bond (or double or whatever) to go through benzene ring?
If not whats the smallest size ring that can have bondings go right through the middle? no fucking clue how to google that

pic related

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>>8285691
The closest I could think of is hapticity, pic related.

>>8285538
Well normally you can get somewhere by going to first principles, so in this case you could say "assume that acceleration is constant", then you get the differential equation [eqn] \frac { \operatorname { d } v } { \operatorname { d } t } = a [/eqn] When we integrate it, we get [math] v = at + C [/math] Now we need to determine C, we can do this by noting that when [math] t=0 \implies v_0 = C [/math]. But velocity is just the time derivative of position, so [eqn] \frac { d s } { d t } = at + v_0 [/eqn] Again when integrating we get [math] s = v_0 t + \frac { 1 } { 2 } at^2 + C [/math] like before we look at when [math] t=0 [/math] notice that this implies [math] s_0 = C [/math] but what's the displacement when t=0? We normally take it as [math] s_0 = 0 [/math]. Which gives us: [eqn] s = v_0 t + \frac { 1 } { 2 } a t^2 [/eqn] The only advice I can give is go back to basics whenever you need to.

>>8285674
Thanks for the help. Another question:

Find the limit of x as x approaches infinity. Equation is ((-e^-3x) - 1)

>>8285702
cooked that ferrocen in a lab once - god was this a bitch too clean from the sublimation apparatus - this also the closest one i knew about but this question came up in a discussion and i had actually no clue how to adress it

>>8285712
That one's pretty simple. Hint: don't get tripped up by the e.

The limit as x approaches infinity of a^x is infinity for any a, given x is positive...

Just installed TensorFlow through Windows Bash and was wondering what resources I should be reading to understand what's going on in example demos.

How would I be able to access the TensorFlow folder with Windows Explorer?

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When doing physics, what are the main things I must pay attention to, to be able to solve the problem efficiently?

Couple of things from the top of my head:
1. understanding what the problem is asking of you to do, find
2. taking into consideration all the physical forces and quantities the problem contains
3. writing down the most basic formulas that relate the aforesaid forces/quantities

Any way to do it more efficiently? What else would you add? Also, apart from using the basic principles and formulas, what's the point of deriving a monster formula that embodies all the tiny basic formulas? Shouldn't I be able to solve any problem by just using the simple basic principles? (btw I'm currently self teaching kinematics, high school level physics, and I'm not familiar with calculus aside from the most basic derivation)

>>8285812
I'm a grad TA who's done a little bit of research with physics education, and the best method to learn introductory physics (imo) is the GOAL protocol. Gather all the known and unknowns in a problem, organize your information (in the form of free body diagrams or velocity graphs or w/e) analyze the data by writing down which equations you need and solving it symbolically (doing everything symbolically is really useful to prevent getting bogged down) and "learn" by plugging in the values, checking your units, and making sure the solution seems physically probable.

>>8285812
This isn't really an answer to your question, but "How to Solve It" by Polya might be a good read if you want to learn about problem-solving technique.

I have some alum I want to use as the electrolyte of a battery for my niece and nephew to play with. I have aluminum foil and copper wire, I suppose those should work well as anode and cathode, what do you guys think? Also what other electrolytes and metals should we try?

How do I know whether a series is conditionally convergent or does not converge at all?

All I was told is ratio, root, direct and limit comparison and integral tests which all check absolute convergence and then Leibniz test which is only for alternating series. What about series like [math]\sum_{n = 1}^\infty \sin \frac{1}{n} \cos \frac{1}{n}[/math], where Wolfram says the series diverges by the comparison test but comparison test requires [math]a_n[/math] to be [math]\geq 0[/math] so all that can be checked is [math]\sum_{n = 1}^\infty \left|\sin \frac{1}{n} \cos \frac{1}{n}\right|[/math] which in fact diverges. How do I check whether [math]\sum_{n = 1}^\infty \sin \frac{1}{n} \cos \frac{1}{n}[/math] diverges?

>>8285102
literally mathematical biology

it's easy peasy math though

Any recommendations on math theories? I mean, books that try to understand the relation between math and other phenomenons (sorry, I can't explain it better)?

I'm especially interested in books about Fibonacci and Pi.

>>8283683
when an object orbits around a certain body, say earth, it's affected by earth's gravitational field, causing the object to accelerate at g, right?
so how come object's vertical velocity doesn't increase over time? please help.

>>8286758
> so how come object's vertical velocity doesn't increase over time?
In a sense, It does; that's why it moves in a curve rather than a straight line. But the fact that it also has tangential velocity means that "vertical" is continually changing.

Really, it's no different to driving around in a tight circle. You're continually accelerating inward, but you never get any closer to the centre.

If x)=[r*cos(w*t),r*sin(w*t)] => dx/dt=[-r*w*sin(a),r*w*cos(a)] => d^2x/dt^2=[-r*w^2*cos(a),-r*w^2*sin(a)] = -w^2*x(t).

IOW, circular motion at constant speed equals acceleration which is always inward.

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Have I been doing math wrong my whole life?
Wtf does he mean when he says the square root does not have 2 solutions?

link>>https://brilliant.org/wiki/plus-or-minus-square-roots/

>>8286974
Yeah, read the "common rebuttals" section.

The function [math]y=x^2[/math] has two solutions. So when you're trying to solve for x, i.e. finding the inverse of the function, you "take the square root of both sides."
[eqn]\sqrt{y}=\sqrt{x^2}[/eqn]
But because [math]\sqrt{y}[/math] only results in positive values of x, you lose one of the solutions. So you have to add a [math]\pm[/math] in front of it. Also notice that replacing [math]\sqrt{x^2}[/math] with [math]\pm{x}[/math] wouldn't make much sense here, anyway. So you get
[eqn]\pm\sqrt{y}=x.[/eqn]

>>8286974
The square root as a function (by definition) only has one solution, the square root as a multi-function (by definition) can, and has, one or more solutions

>>8287004
>>8287033
thanks guys

I must show that u(x) =x*exp(-x) is a solution of y' +y = exp(-x)

My try: u(x): f*g(x) with f(x) = x and g(x)=exp(-x)
so, u'(x) = f'*g(x) + f*g'(x) = 1*exp(-x) + x * exp(-x) = (x+1) * exp(-x) =/= exp(-x)

Why it doesn't work ?

I have to show that the solution of autonomous ODE that are bounded can be be extended for all the reals. How to do it?

Would this spaceship be able to move in reality?

http://www.fastswf.com/555gbdw

>>8287289
Just do it, man.

Some people believe in this "Singularity" even that is suppose to happen in the future.

What is the worst case scenario to happen if this event occurs? What is the best case scenario if does happen? Will humanity be kill?

>>8287304
Plox help

Bamp

>>8285819
>>8285825
Thanks mates!

Is math fun?
How do I make math fun?

>>8287467
Find interesting problems to do

>>8287467
You wade through the huge pile of boring prerequisites until you are at a level where you can even possibly comprehend the actually interesting stuff.

But if you aren't interested in math even in the slightest at this point, that's not going to chance. There is no hope for you. You will never be an autist who spends the majority of his day working through mathematical problems instead of putting his dick inside another human.

>>8287301
bump, the link is harmless, it's an animation I made because I can't explain it properly, I can't make a gif out of it because of a shitty codec and me not having the source file anymore..

something something centripetal force

>>8287202
> u(x): f*g(x) with f(x) = x and g(x)=exp(-x)
> so, u'(x) = f'*g(x) + f*g'(x)
> = 1*exp(-x) + x * exp(-x)
Wrong. It's
1*exp(-x) + x * (-exp(-x))
= exp(-x) - x * exp(-x)

>>8287289
Help

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Is pic related a hack who is wasting is time, energy, and money away?

>>8286736
Godel Escher Bach is a classic. A History of Pi is good but idk how much it fits what you're looking for.

It was casually stated to me that a group whose order is divisible by 2 but not 4 has a subgroup of index 2. Is this obvious?

>>8287004
Thanks for making me feel retarded

I should have intuitively deducted this way earlier, but now I just feel ashamed. Thanks anyway.

>>8287747
I see it now. Let [math]n := |G|[/math] (we'll write this as 2k with k odd for later) and embed [math]G[/math] into the symmetric group [math]S_n[/math] and restrict the sign function. This will remain surjective if [math]G \not \subset A_n[/math], so we need to find an odd permutation in [math]G[/math]. By Cauchy's theorem, we can find an element [math]g \in G[/math] of order 2. The permutation associated to left multiplication by this element splits into a product of disjoint transpositions since the order is 2, and there must be [math]k[/math] many transpositions (i.e. an odd number) because left multiplication has no fixed points.

>>8285218
you can use the fact that F is a center of ∆ABC incircle

Why is the initial velocity of an object the same as the final velocity if it is thrown upwards, neglecting the air resistance?

>>8288066
Conservation of energy dude.

>>8288078
Okay well, I hadn't gotten here yet. Still doing kinematics on Khan Kekcademy.

What's the point of studying when ww3 is around the corner?

There's so much shit going on right now it just seems like it's gonna happen within this year or something

How do I stop worrying and learn to love the bomb?

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>>8288459
1) Stop worrying.
2) Watch anime.
3) Continue life as normal.
4) Hope WW3 advances human technology and you're not murdered. (WW3 has a high chance of not ending human civilization due to nobody winning.)
5) Big fat Anime ass.

If I have a two different existance intervals around different points of the same differential equation and the intersection of this intervals are non empty, does that mean that it must be the same solution for both intervals? Consider that existance and uniqueness has already been proven for this neighborhoods.

Is it possible to one day have technology for the public that can scan the thought of the brain and create an image on the computer.

If such technology was made and widely available how destroyed would the art community of the world be? Would hand drawn artist become rare and valued compared to thought artist (Artist who create image/pictures from their thoughts)?

Any neuro(bio/psych) graduates here that are not working in research?

Im looking for suggestions for jobs. I just feel like theres something great out there that I just cant think of at this time.

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Need some help with combinatorics. I was looking at an old toy which is a dodecahedron with rounded magnetic blocks for faces. There are three blocks of each four different colours red, green, blue and yellow. I wanted to calculate the number of patterns you could create by rearranging the blocks, assuming rotations and colours can be interchanged. The way I went about it is this:
[math]12![/math] ways to arrange the faces
[math]12\cdot 5[/math] ways to rotate since every rotation is defined by a face and one of its 5 neighbours
[math]4![/math] ways to rearrange the 4 colors
[math]3!^4[/math] ways to rearrange the 3 faces for each of the 4 colour groups
[eqn]\frac{12!}{(12\cdot 5)3!^4 4!}=\frac{770}{3}[/eqn]
Since the result is not an integer, I suspect I fucked up somewhere. Any ideas?

Is it at all possible to get a job in r&d in the public sector, and which fields actually get these jobs?

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So, I'm really bad at proving things in geometry, so I'd like to know if this is right:
BOA + AOD = BOD = 180º
AOD and AOB are supplementary
AOD + DOC = AOC = 180º
AOD and DOC are supplementary
AOD and BOC are vertical angles since the sides of one of them form continuations of the sides of the other(Lines AC and BD)
AOD = BOC
E is bisector of AOD and F is bisector of BOC
AOE + EOD = AOD
BOF + FOC = BOC
BOA + AOE + EOD = BOD = 180º
AOB + BOF + FOC = AOC = 180º
AOE + EOD = BOF + FOC
AOE - BOF = FOC - EOD
AOE = BOF = FOC = EOD(since lines E and F are bisector of congruent angles)
As proved here:
AOB + BOF + FOC = AOC = 180º
and since FOC = AOE:
AOB + BOF + AOE = EOF = 180º
Ergo, E and F are continuations of each other.

Now, would someone know any good book that helps get good at proving things in geometry? One that has a great focus in developing skills in proof and whatnot. This is the only thing in geometry that kills me every time.

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10 000 gold coins if anyone can tell me where this term is coming from

>>8289438
nevermind i found it

hey, someone get the fuck in here

>>>/x/18030579

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How do I find A in terms of a and b? (I'm only interested in solving question a. first, please don't go further than this)

Thus far I don't know what to put on the other side of the equation, to isolate a and b. I know that [math]\psi[/math](x,0) must equal 1 in total, and for it to be in bounds for both nonzero conditions it must be less than 1 in either case.

Can I just use substitute a probability less than 1 and sort of hack together an answer? I can also deduce that a is nonzero and cannot equal b. a cannot be 1 because x cannot be equal to 1, it must be strictly less than 1 to save room for the second case, likewise neither can b be equal to 1, and since the two cannot be equal it must be that a<b.

However I foresee that a can equal x, which gives a possibility of using substitution to reduce the second expression to A(1), and placing in the left hand side of the first equation 1-A = A(an x less than a because otherwise absurdly 1-A = A)/a, and this yields A = 1/(x/a +1).

Plugging this new value for A into the second equation gives the left hand side (since a = x) = 1/2, but that's not what I'm looking for so I go and multiply both sides by (x/a +1) and then divide by (b-a) giving me (bx/a -x/a + b -a)/(b-x) and substituting a for x I get (2b-a-1)/(b-a) = A.

But since I didn't use any calculus I'm pretty sure this isn't the right answer. I can only do basic derivatives and I don't see the point in that if there aren't any exponents to kill.

>>8289717

Did you even read the previous sections? Just integrate it with the complex conjugated wave function.

What's the best way to learn general relativity from a rigorous mathematical point of view? I have very little background in physics but a lot in math. I know quantum mechanics and learned basic physics stuff back in high school.

>>8289749
Any GR textbook such as Carroll's or Gravitation will teach you. You may want to brush up on your intro physics before going into GR. Some things will make better sense if you know electricity&magnetism (which provides a strong foundation for special relativity) and optics.

>>8289780
>Any GR textbook such as Carroll's or Gravitation will teach you.

Are they really all rigorous though? The level of rigor in university physics classes is generally abysmal.

>>8289743

brb Khan academy

1. aside of uncertainty and how you can't just reorder measurement, is there any other physical implication of (non)commutativity of observables?

2. what for and how do you commonly use lie algebra, especially in physics? worked example please.

3. https://en.wikipedia.org/wiki/Casimir_element what's so distinguishing about Casimir element?

>>8289749
"General Relativity and the Einstein Equations" by Yvonne Choquet-Bruhat.

>>8289862
thanks!

Does a concept of superposition go against law of excluded middle?

>>8290121
No, since by the time you perform the measurement, only one proposition is true.

>>8290238
I've been reading about it in the meantime and aside from meme answers a lot of people said that the reason why it doesn't defy anything is because it just implies that there aren't definite positions. Would that be true?

>>8284530
please don't trip

>>8287535
try to do a webm fag

>>8288465
this

>>8289717
2/b

How fucking awful of an idea is it to attempt dating within one's graduate program? I imagine poorly as if things go bad, you're still seeing this person regularly for potential years.

>>8290636
>not having regular sex with your adviser

You're missing out mang

>>8283683
I have microwave questions

If I put a cup of water in a microwave oven, it will slowly heat up. If I put three cups of water in a microwave, they will heat up, but more slowly.

>Why is this?

>How safe are microwave ovens for human use? (Eating 'microwaved' food or being near microwave ovens)

>Any other fun trivia about microwave ovens?

>>8290699
Ooh I love this shit.

So water has something known as specific heat. Specific heat is the amount of energy needed to raise the temperature of 1 gram of a substance by 1 degree kelvin, for water its 4.186. So the microwave in both cases is putting in x amount of energy and y is the amount of water so the increase in heat is x/y4.186. Now when you have three times the original amount of water you get x/((3y)4.186) meaning the overall heat increase is less even though the total energy in remains the same.

Being near a microwave ain't that bad but you probably shouldn't rest any electronics on it or put your junk on top while it's running if you ever wanna have kids. If it didn't have a door on it it wouldn't be very good for your DNA as even IR can break some biochemical bonds. Eating microwaved food is fine, it's actually the most nutritionally efficient way to eat food.

If you put water in a completely clean no scratches glass cup and then put it in the microwave it won't boil for a long time. But when you open the microwave and touch it the water will spontaneously become steam and explode burning the shit out of anyone nearby. The same thing happens in reverse if you put the glass in a freezer but it's much safer and cooler to watch the water all freeze suddenly.

>>8284404
Stupid questions, not shit posts

Is there an easy formula for calculating the confidance interval for something such as:
>Getting 40-60% heads after flipping x coins?

>>8290699
Fun fact is that it can charge phones

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Am I a shitty person for not wanting to memorize the physics formulas, and actually want to derive them every single time, because I would rather know how to get to the formula, and also my memory is totally shit? Also, this wouldn't be a good thing to do on a test every time. It is too much time consuming... what do you think?

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How can I solve this, it seems like the operation should only be well defined if the subgroup is normal?

>>8291193

Maths 320 scrub.

The hint is that a coset is not necessarily a group.

>>8284410
Between your 4th and 5th steps when you factored out the "a," how come you didn't multiply the 4s?

Are there any med, neuro or pharm fags here? I take medication for bipolar, many of which help with various different moods.

Lamotrigine ( Lamictal ) 100mg 1x daily for mood stabilization; Bupropion ( Wellbutrin ) 100mg 1x daily for low mood and fatigue; Alprazolam ( Xanax ) as needed 0.5mg up to 2x per day, I don't take this much really anymore; Methylphenidate ( Ritalin ) as needed 5mg 2x daily, I don't have attention problems but I do get anhedonia and this absolutely takes care of it. I have now been given Aripiprazole ( Abilify ) 2mg 1x daily as my doctor a couple years back gave it to me but my insurance said fuck no for the brand name, I brought it up a week ago and now have the script. I read up on it and read that it is a D2 antagonist so wouldn't this contradict the 2 NDRI's I take ( Burpropion and the Methylphenidate ), but I have read studies where it does improve cognitive function. The purpose of the abilify is to keep a more level mood when I tend to me more irritable and the lamotrigine doesn't quite go all the way for me with that. I'll at least give it a try but I would prefer not to waste the Ritalin since I pay out of pocket for it since my insurance company are mouth breathers.

I am a mathematician by training so when I research drugs I can only go so far without obviously doubting myself so I figure you med/pharm/brain fags could help a fellow STEM brother out.

>>8290250
If the proposition is position of a particle or something, then yes, at least in the orthodox interpretation. In general, there is no definite answer to proposition A or its negation until you measure it, at least in the orthodox interpretation.

>>8291487
Want to also add I have been given an SSRI in the past ( Zoloft ) and I had a very bad time with it including total and complete sexual dysfunction and morning sickness, could the Aripiprazole fuck me over similarly? I think I read it has similar functioning as an SSRI. It is an "anti depressant supplement" but maybe not for an NDRI anti-depressant such a Bupropion?

>get Bachelor's degree in physics
>work for 2 years because I need money
>starting Master programme this autumn
>realize I'm too stupid and lack motivation to actually finish it

Should I just end myself?

I love physics, especially cosmology but there's no way I'll contribute anything to the field and it will all just be a huge waste of time.

This is one for you matlab wizzes out there

How do I use laguerreL?

Alternatively how do I enter a value into the k-th derivative of a function.
[math]f^{(k)}(x) = \frac{d^k}{dx^k} (e^{-x}x^a)[/math] where a is a constant
How do I get the value for say [math]f^{(k)}(5)[/math]?

>>8290720
Thanks for your answer, that's all pretty interesting

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>>8290498
had to screen record it, well here you go

>>8292070
Just teach. Easy to find okay teaching jobs with a physics degree. You'll need to teach calc as well though.

Does anyone know of some cool educational videos to help learn about the elements and atomic structure?

>>8292708
No you fag

>>8292708
Periodic Videos. They're not super deep, though.
https://www.youtube.com/channel/UCtESv1e7ntJaLJYKIO1FoYw

They have one video for every element:
https://www.youtube.com/watch?v=6rdmpx39PRk&list=PL7A1F4CF36C085DE1

>>8292717
I have to take a chemistry class and I just want to watch a documentary basic stuff for entertainment. I don't see why this makes me a fag.

>>8292718
Thanks mate.

High school physics, need help, should be easy.

We are bouncing a ball, and making an equation that solves for number of bounces at a given height. No calculus+. The % height retained each bounce is 78%

Anyone help? We had an equation but it ended up being really messy and using logarithms and shit

>>8292731
Let h be the initial height.

Then .78h is the height of the second bounce.

Then .78(.78h) = .6084h is the height of the third bounce.

For the fourth bounce, it's .78(.78(.78h)). You get the idea...

So for each bounce, you're multiplying the height of the previous bounce by .78. Therefore, we can see that the height of the kth bounce is [math]0.78^kh[/math].

So now if we have a height - call it H - then we can set that to our equation and solve for k to get the number of bounces:
[eqn]0.78^kh=H[/eqn]
[eqn]0.78^k=\frac{H}{h}[/eqn]
[eqn]log_{0.78}\frac{H}{h}=k[/eqn]

>>8292748
So "H" is the given starting height. What's the variable "h"?

>>8292750
No, h is the starting height. H is any given height.

>>8292751
I don't think I need both of those. I just need to know how many total bounces the ball will bounce if I bounce it from x height.

>>8292754
For example, we'll be asked:

"The Number of Bounces Obtain at a 2.5m Drop"

We had to determine ourselves what constitues a bounce, and we said any bounce over .5cm is a bounce, anything less isn't.

>>8292754
*if I drop it from x height

>>8292756
Well, you can easily accommodate my solution to that kind of problem. Think of H as a function of k, and note that this function is always decreasing. The more times the ball bounces, the smaller the max height of the bounce. Therefore, you can just plug in your minimum height to get the number of bounces it took to get to that height.

>>8292771
So since our minimum height that we determined constituted a bounce is .5cm, I could just plug in like this?

log0.78(.5/h)=k

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I have pic related. When I type sin(12pi) (in radians), it gives me 4E-13. Why does it do that? Why not just 0?

>>8292774
Yup. Then k is the number of bounces to get to 0.5cm and and anything after that is no longer considered a "bounce."

>>8292775
round off error
this is baby's first numerical methods pls

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>>8292783
I had to make a graph for this, and was surprised that it was linear. Does this look right?

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>>8292805
H is a function of k, so your axes need to be switched. Also, it's not linear. This is what it should look like (note that y = H and x = k here).

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Trying to do the first linear DE problem on Paul's Calc notes.

The stuff above the line is my attempt; the 25 is supposed to be a 50 according to the answer, meaning the factor of 2 I have isn't supposed to be there.

Below the line is how it's actually supposed to be done according to the site, where you don't get two of that term after integrating, but I have no idea what happens between the last two steps I wrote or why my attempt didn't work.

So, where'd I fuck up? This is calc 4 but I feel like my calc 1 knowlage is what's missing. I know I have the right integration constant.

>>8293062

Your notation is fucking ass. Also, all they're doing is just reversing the product rule. Baaby calc shit.

>>8293070
What'd I do wrong though? I multiplied each term by the integration constant then integrated each term. Why'd I end up with twice as much on the left?

>>8292801
Is there some way to fix it? I don't remember any of my other calculators doing it.

How is it that my internet connection has a fucking retarded data cap on it and has a capped speed of 1MB/s. Yet amazing high DPI video can be sent to a TV, no delays, no buffering, no anything? Are the wavelengths used for broadcasting television pretty much like a '4G network' but exclusively for television?

Always has mind fucked me a little when I think about this. If it has the capacity to send high quality video and was already established why wasn't the internet just integrated into it, unless I'm missing something important (probably am).

>>8293291
think you gotta go to
>>>/g/
bud

>>8293306
Pretty sure it's Science and Math related? Has to do with how the fuck data is transferred through thin air which in pretty much physics based

>>8283688
You actually got me, I can't believe I'm still this new after 2 years

I need to learn about Analogue - Digital signals, since I have taken an interest in electronics and electricity in general.

Anybody here could share their experiences? maybe share some book or source for a beginner like me?

Googling this takes me to some complicated text books, specially when I just recently started learning this from the ground up and my knowledge on circuit theory inst that well yet.

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I was reading on the Colossus computer and how it was used to pick German codes and then decoded them.

Also how it was able to read german coded Radio transmissions.

How do you ''read coded radio transmissions''?

https://discord.gg/pzRF5ZM

>>8293357
who is this cosplayer

>>8293386

some Russian cosplayer, just google it, first result I think.

>>8292362
>>8287535

bump

Believe I've asked this before but don't remember what the response was.

Why are Reinmann sums important when definite integration gives the exact area under a curve rather than just an approximation, and wasn't integration discovered before anyway?

Hello,
Why is the primitive function of 1/(1+x^2) = arctan x
while the primitive function of x/(1+x^2) = 1/2 * ln(1+x^2)

>>8294003
I'm dumb, nevermind (calc 1)

>>8293978
Riemann sums are what definite integration is.

MATLAB question

I have
>T=input(' ');
Whatever I type in is displayed in the command window. Is there anyway to prevent this?

Why do farts smell?

>By means of a special process which Wirth had invented, they were burned in the open air without the use of fuel."[55]

How does one burn bodies without fuel?

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What's the mechanism here?
I assume that 2 sulphur gets 2 protons and 2 electrons from a CH3-CH2 couple, forming a 1,3 diene. At this point, there is an attack by other 2 atoms of sulphur, forming a bis-thioketone, which then gives the thiophene through a Paal-Knorr like reaction.

Why does a solar panel have a maximum power output? If in photoelectric effect the intensity of the incident light doesn't affect the energy of the electrons emitted, does that mean that the solar cell reaches a point where it can't emit any more electrons, and that causes the power to max out?

Is there a probability distribution that corresponds with 2^(-(x+1))? I have no idea what that could be

>>8294452
That's just the exponential distribution with lambda = ln(2) and a scale factor.
2^(-(x+1)) = (1/2)*2^-x
= (1/2)*e^(-ln(2)*x)
= (1/(2*ln(2))*ln(2)*e^(-ln(2)*x)

The time between events for a poisson process follows an exponential distribution.

Assuming x varies over the range [0,∞], you need to scale by 2*ln(2), i.e.
P(x)=2*ln(2)*2^(-(x+1))
as the integral of P(x) must equal 1 for a PDF.

As a biology student with 7 months of lab experience at my uni accumulated over holidays (will eventually get more), will I be able to find as much work as a biochemistry graduate or is my degree that bad?

https://www.google.com/patents/EP2623603A1?cl=en

If this method is patented, does that mean no one else can use it?

Also let's say you want to introduce a plant gene into Agrobacterium
Do you
1. Extract total cell DNA from plant cell
2. PCR specific gene
3. Introduce into Agrobacterium via electroporation etc.

How do you ensure none of the genes you don't want arent present in a significant amount? Is that just obvious if you didn't PCR them?
And why do people need to use E. coli between the transfer from plant to Agrobacterium? Why can't you have an Agrobacterium gene library or whatever

>>8294631

fell for the biology degree meme I see

your only hope is study for the MCAT/PCAT and apply to med school or pharm school, respectively

biochem is dirt saturated bc of indians and there is NO skills you can use from your quantitative/physical/instrumental anal/biochem labs that employers on indeed etc actually need for over 30k a year.

Im serious

>>8294709
I'm in the UK, none of that stuff here

>>8294714

you have medical schools and other health related schools

dont go to grad school its a trick, I worked in a lab Spring 2016 with bangladesh students who did NOTHING but research all for a fucking letter of rec and 1000 USD rofl.

ill be around if you have any more questions (will be graduating with biochem degree in May 2017 from st louis university)

>>8293978
>definite integration gives the exact area under a curve
That's true, but you may have a confused idea of what definite integration actually is.

Definite integration is NOT the same as taking the antiderivate and subtracting. Those two operations simply happen to be equal because of the Fundamental Theorem of Calculus.

The actual operation of definition integration is taking the limit of the Riemann sum as the number of "rectangles" under/over the curve approaches infinity.

>>8294714
We have the MCAT senpai. You might be able to get direct second year entry.

>>8294766
into what though and why
I was considering applying for medicine at first but then changed my mind
I don't want to spend my life studying humans exclusively

do biology students end up homeless or something?

Any good websites with math puzzles/problems and shit?

>inb4 project oiler

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is gold specially effective to stop some kind of radiation and what kind is it

>>8295248
how about project Euler?

>>8290699
>>8291033
For that matter, how safe are smartphones?
For every 10 articles that say phones cause cancer and infertility, you can find 10 other articles saying they don't. How much exposure in a day is healthy? Are they still dangerous while turned off?

>>8284105
Almost every interesting bioinformatics algorithm I have seen is an application of graph theory.

Suppose i want to construct a box for sand, that would have a volume of 60 liters and at the same time minimize wall sizes so i will spend the least ammount of money. How do i find the lengths?

I base my education and career off of what /sci/ tells me. Is this a bad thing?

Can science explain why logic works?

>>8283683
+1 for based maharaji

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this is a simple problem but I'm slightly confused
I'm learning about thevenin's theorem and it says the Rthevenin is 300 ohms for this circuit for a load placed between A and B. I'm assuming they did that by adding the left two in parallel and then the 100 ohm resistor in series, but it looks like they are all in parallel to me? what am I missing

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>>8297500
>but it looks like they are all in parallel to me
You should trace out the graph from A to B, making note of where nodes split off and come back together and such. Pic related is an alternate representation. Here you can easily see that the 100 ohm resistor is indeed in series with the 300 and 600 ohm resistors.

>>8297551
I see it now, thanks!

>>8296842
Obviously

Is there any construction of the reals which doesn't involve completeness axioms?

3rd year CS/Math major here. How late is it for me to start prepping for grad school? I think I want to go but all I've done these past two years is nothing but school (grading job and tutoring job but that's it)

I'm joining the programming team and some research program my school has for undergrads. If I can do an REU this summer and start prepping for the GRE now can I get into a decent/fancy/prestigious grad school?

>>8297767
wonders can be done in 1/2 years. do an undergrad thesis, take all REUs you can, talk to big shot professors in your department and ask to do research for them, study and work hard, etc etc

>>8297682
I mean you can build them using the rational numbers (dedekind cuts or cauchy sequence). Neither uses new axioms.

>>8297808
Cauchy sequences imposes the condition that everyone MUST converge. Don't know much aboutt dedekind cuts

I got a real stupid question here. So the sun is around 8 light minutes away. Does that mean that when we look up and see the sun we're seeing where it was physically 8 minutes ago? It's not really in that exact spot?

>>8297814
must? no they don't. the cauchy sequence construction takes all cauchy sequences of rationals (which doesn't mean they converge, just that they're cauchy) and then takes equivalence classes where two sequences are equivalent if they're cauchy together (for example (x) and (y) are cauchy together if (x1 y1 x2 y2 x3 y3 ... ) is cauchy)

the proof that this thing (the equivalence classes) is actually R is not very difficult. see the construction and detailed proofs in Analysis I, by Terence Tao

>>8289857
no one answering my question? is it not stupid enough? or it just overtly stupid to answer?

>>8297818
Yes. This is much more pronounced when we look at more distant objects, and allows us to know some really cool stuff. For instance, we can know what the universe was like 13 billion years ago by looking at objects 13 billion light years away.

>>8297682
The reals are complete no matter how you construct them (except maybe in constructive mathematics).

Tax and all that stuff is taken out of a 'check' from being a graduate assistant, right? I'm just trying to figure out how much I'll make with 10hrs/week at $10.25.

>>8297831
Stone's theorem on one-parameter subgroups says that any one-parameter unitary subgroup can be written as the exponential of a unique anti-self-adjoint operator. This just means that the anti-self-adjoints are the Lie algebra of the unitaries, and the exponential map is injective.

The Lie commutator of two self-adjoints is also self-adjoint, which has to do with the Jordan algebra structure of observables.

do we even have free will? if not, surely there can be only one universe because of the fixed outcomes of all events right? also means true randomness cannot exist, just our understanding of perceived randomness is lacking? if there is no free will, is there really such a thing as crime? free will is awfully convenient when it comes to criminality and justice

if we DO have free will, surely there must be infinite multiverses, for every random choice we made, whether i added this to the thread, whether i posted this on reddit, whether i used a script to get dubs, every word that i typed and erased would lead to a different multiverse?

>>8297931
Kel

>>8297988
what

>>8298004
Kek*

What is the best way to practice integration? Also, what do the guys in those MIT integration competition use for practice?

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Anyone know how the claim in the second to last sentence of the proof follows from the equation?

>>8294256
Anyone?

>>8298390
The LHS is zero. It is given that v and c are nonzero. Thus the product of the (T-lambda[j]*I) terms is zero, so one of them must have zero determinant.

This thread dead?

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Dumb problem that I'm having trouble visualizing.

Suppose there's a simple pendulum of length [math]l[/math], mass [math]m[/math] and angle of oscillation [math]\theta[/math] whose support is moving vertically upwards with a constant acceleration [math]a[/math].

Why is it that the parametric equation for [math]y[/math], in a cartesian coordinate system, is given by

[eqn]y = \frac{1}{2}at^2 - l \cos \theta [/eqn]

Why wouldn't it be [math]y = at - l \cos \theta [/math]?

>>8298637
Nvm, figured it out.

The reasoning is, since the pendulum suffers a constant acceleration in the [math]y[/math]-axis, it's equation is given by [math]\ddot{y} = a \Rightarrow y = \frac{1}{2}at^2 + y_0[/math], and [math]y_0= l \cos \theta [/math], which the contribution due to the motion of the pendulum.

>>8298644
Correction:

[eqn]y_0 = -l \cos \theta[/eqn]

Since it is measured downwards.

>>8288971
pls respond

>>8288971
>>8298812

>A regular icosahedron has 60 rotational (or orientation-preserving) symmetries, and a symmetry order of 120 including transformations that combine a reflection and a rotation.

So if you include just rotational symmetries and mod out by the colors you'll get [math]\frac{12!}{60 \cdot 3!^4}[/math]. There's no need to divide by 4! but otherwise you got it right.

>>8299013
Also: the formula I gave is the number of distinguishable permutations of the sides. So the colors can already be interchanged. If you wanted to preserve the pre-existing partition but interchange the colors you would use a different formula.

It's been nine months since I did my last Math class at a community college, differential equations. What Math should I brush up for my engineering classes and intro Physics courses that I will be doing at the university that I am transferring to?

Are there any math classes where a graphing calculator is not allowed for the exams, but a regular one is?

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>>8289438

how the fuck is sin(x) equal to a finitely long polynomial?

>>8299158

probably applied math courses, pure math usually don't require calculator(sometimes even disallow because of potential abuse) at all because they don't want to waste your time with calculating.

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can /sci/ prove that pi^e - e^pi > 0 without using calculator or approximations method?

or in general for what (a,b) in a^b - b^a = c such that c > 0??

I am reading RBJT Alleby book on Abstract Algebra and holy goly this is the first question.

Is there a way around metric spaces? Because they are some of the proofs I want to do without the use of it; so I could work on the book Principles of Mathematical Analysis by Walter Rudin well for my real analysis course; which has no metric spaces in it... I'm going to be doing it next semester.

Thank you.

>>8299194
Maclaurin series. It basically takes the derivatives of [math]\sin{x}[/math] repeatedly, and apparently there's a pattern in doing it many times which can be predicted with polynimials and factorials.

>>8299484
>Maclaurin series

which is the sum of infinitely many terms, what >>8289438 did was taking an approximation but he put '='

>>8299499
Well it's just a draft, who cares? On an assignment sure, that's wrong notation.

>>8299506

maybe he's an autismo

>>8299511
I didn't see the picture until now and misread 'finitely long polynomial' as 'infinitely long polynomial'. Oops.

So I went to a meeting for this research program at my uni where undergraduates can participate in STEM projects with mentors/professors/faculty/etc
I'm a CS major and most of my knowledge (including programming) comes from my courses, meaning that I haven't done too much outside of school
There was one project that I thought looked cool that dealt with augmented reality but it looked a little difficult for me. There was another project who's leader ended up coming and explaining it to us; I liked the other project more but this one seems less difficult for me

In both cases I would have to learn stuff due to my lack of practical skills, it's just that in the easier one I feel like I'd be less dead weight.

When I asked the presenter if it was okay if my skills weren't up to par and we could learn along the way he said it depends on the project and the people working on it but more or less yes.

Typing this out I think the best answer is going for the "easier" one, something I could probably contribute more to, and just save the harder ones for later semesters. What do yallz think

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Does gravity work like pic related?

>>8299474
What are you trying to prove?

>>8299535
Gravity affects the geometry of space-time, yes

But space-time is not a 2-dimensional surface that all celestial objects sit on top of.

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>>8299549
So it's more like this? Why are scientists looking for a graviton particle then?

>Ring, Fields and Groups by RBJT Allenby
>page 11
>Axiom I :: If U is a subset of N such that 1 E U and such that (a + 1) E U whenever a E U then U = N

okay, I get it, this is induction of N.

but he then said:

>since Z satisfies axiom I

how the fuck are you able to perform induction on Z, start with negative infinity???

>>8299562
The metric [math]{g_{\mu \nu }}[/math] can correspond to a gauge field mediated by a spin-2 boson.

>>8299562
The two images you posted should be thought of as analogies. Obviously it's very difficult to create a faithful representation of gravity's effects on space-time.

The whole "graviton" business is an attempt to reconcile SR with QM, two very successful models that currently have no obvious connection

>>8299593
The metric
g
μν
gμν
can correspond to a gauge

test

>>8299601
>>8299593

how do you write like that? I use Edge so I sure as hell don't have any mathjax extension installed.

>>8299602
leftbracket math rightbracket [math]\LaTeX[/math] leftbracket /math rightbracket

>>8299610

so Edge apparently has a built-in LaTeX support? That's cool.

>>8299158
Precalc?

>>8299602
You use Edge? Really?
Why

>>8299602
>>8299613
>>8299699
what is edge and what does it have to do with tex?

>>8299602
>being this new

>>8299613
No, it's a /sci/ feature

>>8299701
Non-Windows 10 user detected.

Looking for serious books on astrophysics/astronomy for self teaching. Most stuff seems like pop sci level and I want something more in depth, coming from a math major with a decent understanding of physics

>>8299194
> how the fuck is sin(x) equal to a finitely long polynomial?
It isn't. Note the O(x^7) at the end.

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So confused, would i relate the kinetic energy at the end of the fall to the temperature of the rock? but then how would i get the final temp of the rock+water anyway?

>>8300274
wow that seems like a pretty bullshit problem t b h f a m. Good luck.

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if i'm interpreting [math]\Delta S = \int \frac{\delta Q}T[/math] right, trying to cool an object to absolute zero would require an unbounded total change in entropy.

how does that tie in with the 3rd law stating that the entropy of an increasingly cold object approaches a constant value? does the 2nd law instead describe the entropy produced in trying to remove that thermal energy?

how and where do i into microsoft excel

>>8299577

Is he defining Z there? Z is generally defined as an inductive set, I don't think he is trying to prove something is true for all [math]a \in \mathbb Z[/math].

What're the most important programming languages in the aerospace field? C and Python maybe?

>>8300735

Engineering, i mean

If you gathered enough photons into a small space would they eventually slow down and become a solid?

Is it true that carbonated water (without any other additives besides the CO2) will erode your teeth and give you cavities? I had a dentist that swore up and down that this was a terrible thing and just as bad as drinking sodas, and that I must stop drinking them this instant. Made me kind of sad since I own a home carbonator and like the refreshing taste of a nice cold carbonated water.

Implicit derivation of [math]x^2+y^2=1[/math] yields [math]\frac{dy}{dx}=-\frac{x}{y}[/math]. A problem is that the slope at [math]x=1, y=0[/math] is undefined. I have little formal math education so I lack domain knowledge, hence the question: Is there any way to represent derivatives as vectors (perhaps unit vectors)? In that case the derivative at [math]x=1, y=0[/math] could be expressed as [math]\lbrack 0,1 \rbrack^T[/math]. What are these "derivative-vectors" called? Is there even such at thing? What keywords do I need to google for in order to learn more?

>>8301084
I have no clue why the formatting fucked up, sorry. It reads "A problem is that the slope at x=1, y=0 is undefined [...]"

>>8301084
It sounds as if you wan the gradient operator:

en.wikipedia.org/wiki/Del

For an implicit curve (or surface) f(x)=k (vector x, scalar k), ∇f will be the normal vector.

I want to check if [math] y=log(x)+x [/math] is a solution of [math]x^2 y'' + 2xy' + y = log(x)+3x+1 [/math].

[math] y = log x + x [/math]
[math] y' = \frac{1}{x} + 1 [/math]
[math] y'' = \frac{1}{x^2} [/math]

Substitution gives:

[math]x^2 * \frac{1}{x^2} + 2x(\frac{1}{x}+1)+log(x)+x=1+2+2x+log(x)+x=3+3x+log(x) \neq log(x) + 3x + 1 [/math]

I conclude that the ODE is not satisfied but supposedly that's wrong. Where did I go wrong?

>>8301407
[math]y'' = -\frac{1}{x^2}[/math]

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Discuss the relation between a two-dimensional vector and a point in the plane. Discuss the relationship between a three-dimensional vector and a point in space.

>>8301729
A vector represents a point if you choose an origin.