/sqt/ - Stupid Questions Thread

>1/(x^3-1) ----> -1/(1-x^3)?? and then build the series from there?
this is the right way to start

>so it would be -1 + x^3 - x^6+x^9...?
this is wrong though, they should all be minuses

Yeah I caught that when I was writing it down. Thanks!

Here is a dumb one for you: can you recommend a calculator for math up to Calc 1, or an Android app that can replace a traditional calculator? The cheaper the better, I am a poor college student.

I just did an extensive big five personality test, turns out I'm high in neuroticism and agreeableness and very low in openess, creativity and extraversion.

Are there things that people like me can do and be good at or should i just off myself

Why does an Acetic acid + H2O C2H3O2 + H3O

instead of

C2H5O2 + OH- . I know acetic acid is an acid and acts as a Lewis acid, but I dont understand why it couldn't also act like a base in this reaction.
Any insight is appreciated, thanks!

Suppose I have eight socks, two of each color: (e.g. red, white, blue, black). I randomly draw four socks. What is the probability that I have exactly one pair of socks with the same color?

If the exchange rate between euro and usd is 1/1.25 how do I find the reverse?

How many socks do you need to draw to ensure a match of at least one color?

Just set up a proportion.
1 (euro) x(euro)
---- =
1.25 (dollar) 1(dollar)

cross multiply and you are good.

lets say i have a regression
y = b1x + b2x + b3x + e
all it says is that a unit change in a given beta, say b1, changes output(y) assuming all other betas are held constant, correct?
what happens if two or more of the betas change at the same time?

1/(1/1.25)

I make it 24/35.
Sample space is 8!/4! = 1680 (all possible ways of taking 4 socks from a possible 8).
Then we need the number of ways of getting XXYZ (X,Y,Z are sock colours).
There are 4 possible ways of getting XX (4 pairs).
Then there are 6 possible values of Y.
That leaves 4 possible values for Z. (Any of the two colours not yet picked).
Which gives 4*6*4 = 96 ways of getting XXYZ.
Then there are 4!/2! = 12 ways of arranging XXYZ. Giving 12*96 = 1152 possible ways of getting exactly one pair from a set of 8 socks.
Thus the probability of getting exactly one pair is 1152/1680 = 24/35, or approximately 69%.

I then confirmed this experimentally using a Python script.

Find an example of subspaces [math]W_1,
W_2[/math] of [math]R^3[/math] with dimensions [math]m, n[/math] where [math]m \geq n[/math], such that both dim[math](W_1\cap W_2) < n[/math] and dim[math](W_1+W_2 < m + n[/math].

SOS

x-y plane and y-z plane

Getting a PhD in Physics

I graduated in May with a BS in phyiscs to start a job in the semiconductor industry (intel). After 3 months here, the job has gotten mundane, and granted I dont hate it yet but I can see myself growing to hate it very soon.

I'm thinking of going back for a PhD in physics. Should I re-apply immediately? Or should I wait a year to reapply with some industry experience on my resume. Would it look bad if I only stayed at a job for this little time? On the other hand, the job has an R&D title on it so it may look nice on a resume before aplying to grad school. But this also means I'd stay here for at least 2 full years before starting graduate school

Where the heck are the protons gonna go lad

How hard is vector calc compared to calc 2? Calc 2 was pretty easy.

tech support

What is the truth behind Scientology?
Everyone knows that it's a bogus religion that invites rich people to become members to take all their money. Ok yeah.
But most rich people aren't idiots. After all, they wouldn't have made is this far if they were. So there must be something they expect to get out of joining the Church of Scientology. And I'm wondering what that is.
Is it maybe a "muh secret club" thing, because all members are rich?

So this is for matlab.

I have a set of values, G

G=[68 83 61 70 75 82 57 5 76 85 62 71 96 78 76 68 72 75 83 93]

I'm trying to obtain the mode for this, which is 68,75,76, 83. However when I plug in mode(G) it just gives me 68. I have no idea what I am doing wrong here. Pic related.

Oh boy. So my uncle is a member sadly, has an entire bookcase full of L Ron Hubbard shit and various evils of psychology sort of nonsense. I actually have very strong opinions on the cult, but I can't say anything or he'd no longer be allowed to interact with the family.

Anyways the more money you throw at the church, the higher your rank is. Guess who has a lot of money? On top of that the celebrities and artists are basically pampered so these people fall in love with the church, and are more willing to buy their bullshit. Finally, don't overestimate the intelligence of successful people. Steve Jobs thought psychics and fruit smoothies would cure his cancer.

Can anyone recommend good books on biomechanics for a literal retard?

I'd wait desu

Fuck no coz you have n=2 and dim(w1+w2)=3

You must have w1=w2

Pls respond

dim(w1+w2)=3

>dimension of the intersection would not be less than the dimension of either

*correction

Look at the documentation of mode (help mode or doc mode).

Can someone critique this proof of mine? I'm mainly just wondering about the "style" and if the procedure is correct.

Prove by induction that : [math]2^{n} \geq n+1 [/math]

Let [math]P(n)[/math] be the above mathematical statement.

Basis: [math]P(1):[/math] [math]2^{1} \geq 1+1 \implies 2 \geq 2[/math] , holds true.

Inductive Step: Assume [math]P(k)[/math], [math]2^{k} \geq k+1 [/math] holds true. Thus [math]P(k+1)[/math], [math]2^{k+1} \geq k+2[/math] will hold true as well. Proof:

Consider [math]2\cdot P(k)[/math], that is: [math]2^{k}\cdot 2 \geq 2\cdot \left( k+1\right) \implies 2^{k+1} \geq 2k+2 [/math]

Since [math]2k+2 \geq k+1 [/math]. [math]P(k+1)[/math] holds true.

So by PMI, [math]P(n)[/math] is true.

We landed a person on the moon with a computer as good as my apple watch 50 years ago.
instagram.com/p/BZA0s7EAmF1/?taken-by=elonmusk
now we have super computers and shit, why are we still having problems?

it's fine, just don't forget to specify you're in N or R+, or wherever, that last bit about (2k+2)>(k+1) does not hold for a real k

My hand-waving proof would go like this:

We have
[math]2^0 \geq 0 + 1[/math]
and
[math]\mathcal{O}(2^n) \geq \mathcal{O}(n)[/math]

Thus [math]2^n \geq n + 1[/math] for [math]n \geq 0[/math].

But there you are misusing big O notation, which makes you seem retarded

Ah yes, thank you for pointing that out.

>We landed a person on the moon

>Using big O's as variables

Compsci alert

>Retard alert
ftfy

>Basis is 1
???

[math]0 \not\in \mathbb{N}[/math] here

Always found vectors and matrices much easier than summations.

Bump

>android app
TI calculator emulator
your professor certainly won't let you use your phone in exams though

you seem to be under the false impression that
a.) 90% of humans aren't complete idiots
and
b.) being rich somehow requires personal merit rather than just inheriting parents' money or being a pretty face for the movie cameras

Have to show the conditional statement is a tautology without truth tables.

(p∧r)-->p

Would it be okay if I just say
>True except T-->F
>in which case the conditional statement would have to be (p∧r)-->¬p

Shouldn't white holes also be invisible/undetectable?
>The opposite of a black hole > something where nothing can enter > it can't reflect light

Why is assumed that if white holes existed they would spew out information if they can't hold any information in the first place?

How could you ever detect a tachyon if they were real?

It was worse than your Apple watch.

This is the De Moivre formula
Its proven by induction
for n=1 its a trivial statement
now assume its true for some n, and see if u can prove for n+1

Because it's a stronger acid than water

I just bought Michael Artin's 'Algebra' and I struggled through the first chapter, I am considering saving Michael Artin's book for later and studying linear algebra now. What would be a good textbook for linear algebra if I really want to learn Modern Algebra? I don't have much knowledge in matrices other than the first chapter of Artin's book. Thanks.

goodreads.com/book/show/554752.Algebra_I_for_Dummies?ac=1&from_search=true

Guess you want "Linear Algebra For Dummies"
The simplest explanation is usually the best.

Don't listen to .
Get yourself a copy of Charles Pinter's "A book of Abstract Algebra." You can thank me later.

I think and would be a good combination. You don't need that much linear algebra to start studying modern algebra.

Help with babby analysis.

Let [math]A[/math] and [math]B[/math] be two nonempty sets of real numbers that are bounded above and below, respectively. Let [math]s = supA[/math] and t = [math]infB[/math]. We form the set [math]C={c=a+2b:a\in A, b\in B}[/math]. Prove or disprove: [math]supC = s+2t[/math].

What I have so far:

Let [math]s=supA[/math]. This means [math]\forall\epsilon >0, \exists a\in A, a>
s-\epsilon[/math].
Let [math]t = infB[/math]. This means [math]\forall \epsilon > 0, \exists b\in B, b < t +
\epsilon[/math].
Prove [math]supC=s-2t[/math]. Prove [math]\forall\epsilon > 0, \exists c_0\in C,
c_0 > s-2t+\epsilon[/math].
Fix arbitrary [math]\epsilon > 0[/math].
By first assumption, know [math]\exists a_0\in A, a_0 > s-\epsilon[/math].
Likewise, know [math]\exists b_0\in B, b_0 < t + \epsilon[/math].
Choose [math]c_0 = a_0 - 2b_0[/math].

I think this will work out, I'm just not sure how to connect the inequalities.

Fucked up the problem statement.

We form the set [math]C=\{a-2b:a\in A, b\in B\}[/math]. Prove or disprove: [math]supC = s - 2t[/math].

Bonus:

[math]A, B[/math] are bounded below and [math]B\subseteq A[/math]. Prove inf[math]B\geq[/math] inf[math]A[/math].

Gah, I perfectly understand why this is true, I just can't finangle with the epsilons to prove this. I want to say, assume for contradiction that infB < infA, this means there's some x sandwiched between which violates the subset property, but I can't formalize that...

because new things are new
we've never landed a booster before, so HOW to land one was unknown
Now we do know, and we're getting closer and closer to perfect landings

do remember that the Apollo missions had many very near failures, saved only by a hair for a few of em

dude this is obviously not true. counterexample is easy.

The only group homomorphism from [math]S^3[/math] to [math]\mathbb{Z}[/math] is trivial, right?

what group operation on [math] S^3 [/math]?

See

hint: [math]\inf B < \inf A[/math] means that [math]\inf A - \inf B > 0[/math]. Use this as your [math]\epsilon > 0[/math].

[math]a_0 - 2b_0 > s - 2t -3\epsilon[/math]

I'm retarded, I meant [math]S_3[/math] and not the 3-sphere.

then yes since for any homomorphism f, |S_3/ker(f)| = |im(f)| forces im f=0 and so ker(f)=S_3

I am but a humble layman and the explanations that I heard or looked up with regards to what generates lift were dense and confusing, is my pic wrong?

Thanks senpai. I admire your dedication

I don't know if your picture correct, but have you looked up 'Bernoulli's Principle'

I read about an algorithm in a paper on arxiv and I asked the author if he could send me an implementation of his work. It's been months without a reply. What should I do?

lift is an immensely complicated concept, even if we are only concerned with ideal fluids the two main explanations for lift are pretty incomplete.

If you just want to gain an intuition for lift focus on the Newtons's third law explanation and conservation of momentum. If you want to get a bit fancy you can then learn the Bernoulli's principle explanation and conservation of energy

your pic isn't "wrong" but it is really shitty, even for the basic explanations, and the block of text on the right is completely retarded.

Thanks!

Can you show how to get that? I'm just not seeing it.

Thanks for the info.

Thanks a ton guys.

Send him another letter. Send him one every week. The squeaky wheel gets the grease.

kek, dont do this

What does [math]2^A[/math] mean when A is a set?

en.wikipedia.org/wiki/Power_set

and more generally X^Y denotes the set of functions from Y to X

Thanks, friendo.

What can I do with a bachelor's in physics? Except kill myself

just came into Veeky Forums for the first time worried about finding a place to ask a dumb question, so thanks for having this thread exist. If a surgeon finds previously unknown problems/damage during surgery, how likely would it be that they 1) fix the problem and bill you after, or 2) tell you about it after to schedule a second operation. thanks.

Why can 1g of centrifugal force not replace 1g of gravity? With our current level of technology we could easily redirect a suitable asteroid to geosync orbit, use nukes to smash a habitation chamber along an axis, rotate and done.

I'm looking to do some scoring analysis for a design competition prompt where the prompt gives equations that define the scoring guidelines. Are there any tried and true methods for doing this?

i've graduated college and i don't think i understand electricity and magnetism well.

i also want to understand modern physics.

what online resources do you guys suggest for a comprehensive understanding of these topics?

>Educational advice.
>Be taking macroeconomics.
>Teacher is bro-tier.
>Can't stand his lecture style.
>I want to drop and take the class later because I'm in no rush to get this class out of the way. It's not important to get it done this semester.
>Should I drop and retake later? I get most of the money back. Pretend that's not an issue.

Guys, any good resources for Radiometry and Photometry? (Calculus-based)
Preferably videos, but, they I can't find any.

And some Thermodynamics and Fluid Mechanics resources as well..

THanks!

Most people on here don't have a PhD, and I wouldn't be surprised if most didn't have at least an associate's or bachelor's degree.
I don't have a PhD, but industry experience might help you get accepted, for whatever that is worth. Of course, you probably knew that.
If your grades for your B.S. didn't suck ass, you might wish to apply so you don't waste any time.

I'd be interested to know this as well.
Books that I can get a free PDF of would be most welcome, but the book name is really all I need.

Have a great fucking time studying more.
Relax, bud, it isn't the end of the world. If I were you, I would strive to learn more and eventually get a higher level degree, so to speak. You could always educate morons on Veeky Forums in your spare time.

Ultimately, knowledge for the sake of knowledge isn't the worst thing in the world, you know?

Also: kek

If you wish to learn the subject, and the lecture style gets in the way of that, drop it.

Others might tell you to suck it up and study on your own time, which isn't terrible advice, but I'm practically retarded, so lectures help me greatly.

Only drop if you wish, and it won't fuck you over. Good luck, babe.

Thanks user. You're alright.
I'm going to get a study group together, suck it up and take the first test and if that fails then I'll chuck it.
Happy studies.