/sqt/ Stupid Questions Thread

This thread is for questions that don't deserve their own thread.

Tips!
>give context
>describe your thought process if you're stuck
>try wolframalpha.com and stackexchange.com
>How To Ask Questions The Smart Way catb.org/~esr/faqs/smart-questions.html

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Other urls found in this thread:

purplemath.com/modules/specfact2.htm
Veeky
en.wikipedia.org/wiki/Geometric_series
en.wikipedia.org/wiki/R/K_selection_theory
amazon.com/Calculus-Made-Easy-Silvanus-Thompson/dp/0312185480/
amazon.com/Manga-Guide-Calculus-Hiroyuki-Kojima/dp/1593271948/
amazon.com/Calculus-Lifesaver-Tools-Princeton-Guides/dp/0691130884/
amazon.com/Calculus-Intuitive-Physical-Approach-Mathematics/dp/0486404536/
en.wikipedia.org/wiki/Types_of_snow#On_the_ground
twitter.com/SFWRedditGifs

Hey, can someone suggest a good book to learn Power series from? I'm an undergrad and i would really like to know how to find the values of many series. Please suggest some sources.
Thank you!

you're not going to find a book on just power series, or just series for that matter. the princeton "cracking the math GRE" book has a good section on series and sequences

what's a good book to give me an intuitive understanding of calculus?
preferably something that isn't 1500 pages

Does [math]\displaystyle \mathbf{F} = \frac{ \mathrm{d} \mathbf{p} } { \mathrm{d} t}[/math] still hold in non-inertial reference frames?

Show that if [math]x \in \mathbb{R}[/math] and [math]0 < x < 4[/math], then [math]\frac{4}{x(4-x)} \geq 1[/math].

The easiest way is to show this by cases right? Doing it when x = 2 is easy, but I have no idea what to do when x < 2 and when x > 2. Like I get that that the denominator will be the greatest when x = 2 and smaller for all other values within 4, but I don't know how to show it.

Conceptually speaking, in what way is an integral an "anti derivative"?

As I understand it, derivatives are changes of one property with respect to another calculated by tiny points converging to a particular point. Integrals are the combination of tiny points. How does that make them inverse?

How do you guys get jobs in a field outside your degree? I just got an email from my school saying there's openings for a bank, but I'm in engineering, and I think I would fuck something up for the company if I managed to get hired.

What exactly is your question?

Engineers probably know enough math to work at a bank. More than theyd need really. What position is it for?

As to how, you apply for the job and write a brief statement that tells them you believe your education and knowledge could be beneficial for the position despite not being a finance degree

Im struggling in advanced calc, will I struggle in abstract algebra too?

>he doesn't know
most engineers don't do engineering. I work at a fortune 50 company, my job title is engineer, but all i do is manage projects and move money around.

>professor wants to know our long-term career goals

Is it okay if I just say I want to be a scientist?

Here were the positions. I don't know if I could get the job yet since I'm in 2nd year as an undegrad. I'll probably continue doing part-time work in the summer at my brother's place though doing basic network engineering work.

Integrals are not antiderivatives. It's just a shitty notation, confusing people.
They are not entirely unrelated though since [math] \int_a^b f(x) dx = F(b) - F(a) [/math], if [math] F'=f [/math] in some region containing [math] [a,b] [/math] .

What is "advanced calculus"?

it's the high school level calculus class for the "advanced" kids.

At my uni "advanced calc" was real analysis. Not sure if this is true everywhere. Basically calculus but the emphasis is on proofs instead of computation.

advanced calc was a 3rd year course that covered stochastic calculus and calculus of variations. you could pick between that class and PDE's

Alright, so I understand what is happening here but I can't for the life of me figure out how I reach n(n+1)/2 . We basically create the sum of n - 1 until we reach 1, but how do I reach that formula where I can just insert n? I can't wrap my head around thinking in that manner if you know what I mean.

Oh that sounds interesting. My uni has a calculus of variations class on the catalog but it always gets cancelled due to low enrollment

[math] \sum_{k=0}^{n-1} (n-k) = \sum_{k=1}^n k [/math]

Literally reverse the order of the sum and you get Gauss' formula.

Oh yea, I suppose that's true.
I'm not a math student or anything, am I supposed to just remember that or what?

So I have to solve this equation:
[eqn]u_{yy} - \frac{1}{(2x+1)^2}u_{xx} - \frac{2}{(2x+1)^3}u_{x} = 0[/eqn]
They ask me to solve it by putting it in its canonical form, which I manage to do no problem. But then how the fuck am I supposed to solve this bullshit?

[eqn]v_{\xi \eta} + \frac{1}{(2x+1)^2}v_{\xi} - \frac{1}{(2x+1)^2}v_{\eta}=0[/eqn]
where
[eqn]\xi (x,y) = y-x^2-x,\thinspace \eta(x,y)=y+x^2+x[/eqn]

How the fuck do I get [math]v[/math] from there? I'm pretty sure it's not wrong because several people have got to that equation and asked me how to do it, and I just don't know.

>am I supposed to just remember that or what?

Well, Gauss' formula is pretty beautiful so you can memorize it just by instinct. I never actually sat down to memorize it, it just naturally digs itself into your brain because of how useful it is.

But if you are that lazy then simply remember that you can deduce Gauss's formula, and the formulas for [math] \sum k^a [/math] in general via summation by parts starting from the obvious fact that [math] \sum_{k=1}^n 1 = n [/math].

It's okay to not know and admit to it. Just bee urself, honestly.

I'm pretty jelly right now, my shitty uni doesn't have nice things like those. At least there's always the library, though.

name a more pretentious calc book. I'll wait

When youve taken ode, you could take any of those for sure. Could probably do most of them right now

Real analysis

what are some real life applications of calculus?

We're in a junior level class and most people are going to say they want to be a doctor. I know I want to do research/teach, what kind? I have no idea tbqh.

Economics.

See, in our modern world there are too many pathways to success, but the wealth that we currently have and can produce is finite. It can only be split so thinly. So we have to face a reality: Either we all share it equally and basically, everyone is poor, or we create some kind of division between the rich and the poor so that the poor get scraps, and the rich get a lot. And here is where calculus comes in.

Can you pass the calculus sequence? Congratulations! Pick your job as an economist, engineer, physicist, computer scientist, etc. And then come to one of the thousands of corporations ready to pay you top dollar so that you can enjoy a great life.

You can't pass it? Congratulations! Head on over to the liberal arts to get ready for a life as a Starbucks barista making minimum wage. Thanks for playing!

Calculus is literally holding our economy together. It is the buffer. The limiting factor. It makes it so only a select group can become rich and powerful. And no one can argue with it because math is objective. You can't really go out crying that calculus is discriminatory unless you want to openly admit to being an absolute retard. And no one's pride is so low that they would publicly admit they are dumb. So society keeps working as intended. Thanks, Newton!

Could you please be more specific? Like state prominent examples like the Black-Scholes Equation

You didn't actually read my post, did you?

By conditions on x you get that [math]x(4-x)>0[/math] and can multiply both sides without worries, so [math]4\geq 4x-x^2\to x^2-4x+4=(x-2)^2\geq 0[/math]. Squares of reals are trivially non-negative.

tie in pic looks ridiculous

I did and I see how the gradient of the supply and demand slopes are of great significance, however, I was wondering if you could state a few more examples that involve some sort of derivation or integration.

Fuck off bootlicker

You cant even get basic math right but youre trying to answer a question on calculus.

Retard, the top 10% of people own over 50% of the wealth on tbe entire planet. If that 50% of wealth was redistributed equally, the vast majority of people would see INCREASE in wealth.

Calculus is not tbe limiting factor between the rich and poor. Put a day 1 calc I problem in front of Trump and see if he can solve it. Or Steve Jobs or Bezo or Koch or Mercer. None of those rich dumbasses know calculus.

Most engineering fields use it regularly. Building infrastructure, new technologies. Most physicists probably use it in their research. Biologists might use it to model bacteria growth or something. Economists, actuaries use it for optimizations. And more

Let [math] x \in (0,4) [/math]. In this interval we have that [math] x(4-x) > 0 [/math] which means that we can manipulate inequalities without changing signs: So

[math] \frac{4}{x(4-x)} \geq 1 \iff 4 \geq x(4-x) \iff x^2 -4x + 4 \geq 0 \iff (x-2)^2 \geq 0 [/math] which is trivially true.

>the vast majority of people would see INCREASE in wealth

Yeah but that "increase" would still put them below the poverty line. Do you know how many people there are alive today? Go on, pile up all the wealth and then give everyone an equal amount of it. You will be lucky to end up with 5$ each. Good luck with that mate.

>Put a day 1 calc I problem in front of Trump and see if he can solve it. Or Steve Jobs or Bezo or Koch or Mercer. None of those rich dumbasses know calculus.

That is not what I meant, which shows in what category you belong to lol. I said that Calculus is just the buffer. If you pass it, you are good. You don't need to keep knowing calculus. You know what major Trump studied, which means he had to pass calculus and he did. So he was allowed into the big boys club. After that it was his other actions that decided how rich he got, but getting into the big boys club guaranteed he would at least be middle class. The same goes for everyone else you listed.

If Steve Jobs had fucking failed calculus do you think he would have had the opportunity to start a corporation? If he could not pass calculus, his IQ would be approximately 80. He would be lucky to be able to tie his shoes.

Well, if it's real analysis, then maybe you can do ok in Algebra. Algebra has a more "natural" way of thinking.

>iq memer
>bootlicker
>"corporations are great!"
>im wrong? move those goalposts!
>calls calculus a buffer but cant do an optimization problem
>thinks wealth necessitates intelligence

is race "r e a l"?

how can a calculus book be pretentious?

>"corporations are great!"
Never said that. But corporations are great at making big money. If you deny that, you are retarded.

>thinks wealth necessitates intelligence
Have you ever observed how stupid people use their money?

>Write down the balanced reaction equation for the reaction of chromium oxides with nitric acid.
>What kind of reaction occurs?

>write down the balanced reaction equation.
ok, I can do that.
>for the reaction of chromium oxide with nitric acid.
So, do they want me to guess the product?
>What kind of reaction occurs?
Yeah, a reaction.
So, is there a special kind of place I need to look up how to monkey see and monkey do?

Why the FUCK is n^3 + 1 NEVER prime (except when n=1)

I can trivially prove it for odd n but can't prove it for even n

help

I keep breaking pens.
How do you deal with the frustration of not understanding?

>name a more pretentious calc book.

The statements contradict each other what the fuck am I supposed to do

>Why the FUCK is n^3 + 1 NEVER prime (except when n=1)
>I can trivially prove it for odd n but can't prove it for even n
Plug (2n)^3+1 into Wolfram, and it'll show you that (2n)^3+1=(2n+1)(4n^2-2n+1)

Also it's just the sum of cubes formula
purplemath.com/modules/specfact2.htm

Oh duh I was just staring at that. Thanks my negroid

Is this true or not?

[math] \sum_{k=1}^n ( \lg (n) - \lg (k)) = O(n) [/math]

>Is this true or not?
Why might it be true?

Say you have an infinite lattice of points and paths that connect them such that at any point there are 4 paths leading away from it. Further suppose that you pick a path at random, then what is the probability that you will eventually reach a point one "step" away?

The way I worked this is:
Probability of getting to the point after one step: [math] \frac { 1 } { 4 } [/math]
After three steps: [math] \frac { 1 } { 4^3 } [/math]
After 2n+1 steps: [math] \frac { 1 } { 4^{(2n+1)} } [/math]

So we end up with the series:
[eqn] \frac { 1 } { 4 } \sum _{ n=0 } ^{ \infty } \frac { 1 } { 4 ^{2n } } [/eqn]So we get a probability of reaching the neighboring point of: [eqn] \mathbb { P } = \frac { 4 } { 15 } [/eqn]

Does that seem right to everyone else?

>Probability of getting to the point after one step: 1/4
Shouldn't this probability be 1?

Why is some snow easier to pack into snowballs than other?

Why would it be? By hypothesis you have a 1/4 chance of picking the path that takes you the end point on your first go.

>The term Advanced Calculus has come to mean different things over the course of the past century. During the first half of the 20th century, Advanced Calculus courses consisted of what's now commonly found in Multivariable and Vector Calculus possibly with some Differential Equations topics thrown in. Lately, it has been fashionable to call very watered down "Real Analysis" courses Advanced Calculus even though it's not [math]advanced[/math] nor [math]calculus[/math] and goes no deeper into analysis than a good rigorous calculus book does. Here Advanced Calculus means what the name implies, advanced topics in calculus (and tools from analysis) typically not found in the usual calculus sequence but still very useful for solving difficult problems in science, engineering, and mathematics.
>Veeky Forums-science.wikia.com/wiki/Mathematics#Advanced_Calculus

>Why would it be?
After one step you have reached a point one step away.

>Early Transcendentals
All that mean is they cover the Transcendental functions early (trigonometric, exponentials, logarithms) rather than wait until they get to power series and DEs to define them by calculus.

Also Rogawski is terrible for self study.

No, you have a 1/4 chance of reaching the end in one step.

>No, you have a 1/4 chance of reaching the end in one step.
So when you said
> Further suppose that you pick a path at random, then what is the probability that you will eventually reach a point one "step" away?
You had a specific point in mind of the four that are one step away? In that case the probability of reaching it after 3 steps is certainly higher than 1/4^3, I count at least 7 walks

>You had a specific point in mind of the four that are one step away?
Yep.

> I count at least 7 walks
How?

>How?
If the end point is the one above your starting point, then you can do (L= left, R= right, U=up, D=down):
LUR, RUL, DUU, UUD, UDU, LRU, RLU

Yeah, just realised that. Thanks user.

What is the product of every number greater than 0? I think it's 1, but not sure

>I think it's 1
That's correct.

Eh, sure it isn't undefined?

Depending on how you pair the infinitesimals and -->infinites you should be able to make it sum whatever as you take the limit.

>Eh, sure it isn't undefined?
\prod_{x>0} x =
1(\prod_{x>1} x)(\prod_{x1} x)(\prod_{x>1} 1/x) =
\prod_{x>1} 1 =
1

Ah right yeah no bypassing numbers, no funky summations. You're right.

Why the shitnigger does

2^0 + 2^1 + ... + 2^n = 2^{n+1} - 1

@perfect binary trees

>Why the shitnigger does
>2^0 + 2^1 + ... + 2^n = 2^{n+1} - 1
en.wikipedia.org/wiki/Geometric_series

o fuck

How important is the right latin ending of a word in an anatomical context really?

Assuming knights are honest and knaves lie:
There must be some knights, and it can't include U. If he was a knight, he's lying. If he's not a knight, there must be another to make sure he's lying.

Of X, Y, and Z: mutually exclusive. We have to look at V and W.
If Z is a knight, W is a knight. Z is now lying, so he's a knave.
If Y is a knight, W is a knight. Everyone else is a knave, so this works.

For the sake of completion, X is trivially a knave just by looking at Y and Z.

Look at it in binary
1 + 10 + 100 + ...

>Assuming knights are honest and knaves lie:
So THAT'S the missing knowledge he couldn't tell us

Good observation

how do babies make any evolutionary sense? they are completly dependent untill about age 7 or so, so for those 7 years you have to waste time and energy to this thing that cannot fend for itself

protip to help you remember pi you can use the apporimation 314,159/100,000

>how do babies make any evolutionary sense? they are completly dependent untill about age 7 or so, so for those 7 years you have to waste time and energy to this thing that cannot fend for itself
en.wikipedia.org/wiki/R/K_selection_theory

i have the first 60 digits of pi tattooed on my dick so if i ever need it on a test, i just get hard on the spot. fuck memorization

If the uniform metric C(X,Y) on metric spaces X and Y is complete, does that entail that Y is complete?

Can anyone give me a straight answer on what specific algorithm's are used to generate/compute new prime numbers are? I really would like to know because I think I may have stumbled onto a relatively trivial way of computing increasingly large prime numbers but I feel like it may already be utilized and I honestly don't even fully understand why it works.

Pic unrelated btw

Anyone have any good recs doe basic logic? I remember taking an intro to logic class back in college. I don't remember a lot, just basically that it was 'math with words' I remember one of the rules was a motis ponens(sp?) and it basically let you set up logic problems and use those rules to confirm or deny. I'm just looking for a decent comprehensive book that will cover the basics.

i saw this exact post work for word on r badmath you fucking c*ck. go back to r#ddit

non-inertial reference frames are garbage; it's hard to predict anything with them. dp/dt is the definition of force, so it always applies, but it will be meaningless in a non-inertial frame.

Could you please attempt to offer an intelligent answer to my question instead of acting like a cunt to stroke your e-peen? It's a legitimate question that I've been going in circles trying to find a straightforward answer to.

-U cannot be a knight
-X contradicts Y and Z, thus he cannot be a knight
-Of the remaining possible knights, V can only be in agreement with W. This falls short of 3, so V cannot be a knight.
-if Z is correct, then W is also correct, leading to a contradiction. Z is not a knight.
-at this point we've eliminated 4 of the 6, so W is correct. If Y is wrong, that would make Z correct, leading to a contradiction. Thus, W and Y are knights.

Let [math] y_n [/math] be a Cauchy sequence of [math] Y [/math] .
Consider the sequence [math] f_n [/math] of [math] C(X,Y) [/math] where [math] f(x)=y_n [/math] for all [math] x \in X [/math] (constant functions).
[math] d(f_n,f_m)= \sup_{x \in X} d(f_n(x),f_m(x)) = \sup_{x \in X} d(y_n,y_m) = d(y_n,y_m) \to 0 [/math] (d denotes three different metrics here)
Therefore [math] f_n [/math] is a Cauchy sequence of [math] C(X,Y) [/math], and since [math] C(X,Y) [/math] is complete it converges to some [math] f \in C(X,Y) [/math] .
[math] f [/math] has to be a constant function as well since [math] d(f(x_1),f(x_2)) \leq d(f(x_1),y_n) + d(f(x_2),y_n) \leq d(f,f_n) + d(f,f_n) \to 0 [/math] which implies that [math] d(f(x_1),f(x_2))=0 [/math] , which means that [math] f(x_1)=f(x_2) [/math] for all [math] x_1,x_2 \in X [/math] .
Denote with [math] y [/math] the constant value of [math] f(x) [/math] .
[math] d(y_n,y) = d(f_n(x),f(x)) = \sup_{x \in X} d(f_n(x),f(x)) \to 0 [/math].
So, [math] y_n \to y [/math] .

What are some of the best resources for Chem E Transport? Also, is it actually important or just a way for Chem Es to stroke their egos? Either way, resources please, my prof isn't doing it for me and I'd like to learn.

>short
amazon.com/Calculus-Made-Easy-Silvanus-Thompson/dp/0312185480/
amazon.com/Manga-Guide-Calculus-Hiroyuki-Kojima/dp/1593271948/

>long
amazon.com/Calculus-Lifesaver-Tools-Princeton-Guides/dp/0691130884/
amazon.com/Calculus-Intuitive-Physical-Approach-Mathematics/dp/0486404536/

Veeky Forums-science.wikia.com/wiki/Mathematics#Proofs_and_Mathematical_Reasoning

Veeky Forums-science.wikia.com/wiki/Chemical_Engineering#Transport_Phenomena

It's easiest when it's near 0C. Pressuring the snow melts a fraction of it, and the water acts as glue.
See P* at en.wikipedia.org/wiki/Types_of_snow#On_the_ground

Ok guys, Im a MSc biochemistry student about to do a lab internship. How can I be creative enough to plan and conduct my own research about a certain matter? I really want to do my best and try to impress my supervisors to get a job here.

Not a chem eng major but some who are have said its their first real class so Id say its important

What I did for my project (not in chem tho) was search google, arxiv and any other relevant sites for the latest research in my field and found a topic that looks interesting/i had the resources for doing.

My professors are utterly useless, if yours arent, you should talk to them

yeah, can try to impress them with knowledge on recent research, but in the end, they know it better, and you are supposed to do what they ask or tell you to do