/sqt/ stupid questions thread

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

youtube.com/watch?v=bS4jPjs6JPw
tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsPtI.aspx
lmgtfy.com/?q=why does IQ matter
en.wikipedia.org/wiki/Polynomial_long_division
en.wikipedia.org/wiki/Mathematical_induction
khanacademy.org/math
aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer
detexify.kirelabs.org/
twitter.com/SFWRedditVideos

What are some applications of Bézout's theorem to basic projective geometry. Two degree one curves intersecting seems kind of trivial, since in a projective space anyways parallel lines will meet.

Ayyyyyy
How many things are emergent properties of the interactions of fundamental particles? (Eg distance, gravity)
Is there a lower level of reality than fundamental particles, and what is it?

Basically, what things are the results of the interaction/nature of fundamental particles, and how do you get from them to the thing that is an emergent property of them?

think I found a proposition: If [math]f(x,y)[/math] is a homogenous polynomial of degree [math]d[/math], then [math]Z(f)\subseteq \mathbb{F}P^{n}[/math] has at most [math]d[/math] points.
stinks of Bézout.

how did we get pictures from voyager?

Like this

youtube.com/watch?v=bS4jPjs6JPw

I wanted to get in a CompSci college but barely failed the exam and got redistributed in a traffic and transport college in the same uni ,my aunt who is a teacher at that uni (and teached me math and phys for the exam because I was a brainlet in highschool) and my family all told me it would be better to stay in that college after a year has passed so the year I spent there would not be wasted ,so I did ,even though I felt it was a huge mistake now almost two years later I feel like this degree can't get me a good rewarding job and that thought took all my motivation away I can't sleep and I feel like I don't have anything to get up in the morning for
So I want to ask should I quit this college and go for the compsci degree and a job in programming?And what's a good job that I can aim for with a traffic and transportation degree?

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Why the fuck are trig Integrals so complicated

they aren't
just memorize reduction formulas

Who "dreads" series? Series as a subject are way easier than antiderivatives.
There's like 4 or 5 convergence tests you have to know, just practice enough to develop a feeling for when each one works and the rest is autopilot.

be comfortable with simplifying factorials in different ways, learn each test, do a bunch of practice. it's really no worse than the rest of the course.

Think you're a minus sign off. See tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsPtI.aspx explanation above third green box

I need some form of strictly noncommutative algebra (i.e. a*b != b*a for all distinct (a,b)) for an proof attempt at representing combinatorical objects algebratically

The only noncommutative algebra I know of that can be calculated easily are matrices but they don't suit my needs. Are there any other such systems?

due to representation theory you're going to find matrices if you want regardless

Can anyone give me some links to me that prove IQ matters?

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lmgtfy.com/?q=why does IQ matter

How should I go about this?

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There is something about vector analysis that is just so damn sexy.

sorry i just realised it's not clear from my question, but F is a vector field

What have you tried?

how do i prove that the intersection of two distinct planes is a straight line?
i've started by considering two distinct planes [math]n_1\cdot (x-x_0)=0\,,\quad n_2\cdot(x-x_0)=0[/math] where n1 x n2 is non-zero, but that's it, and idk how to proceed. I imagine the cross product will be involved since the direction of the line is ±n1 x n2, but can't think how to use it with where i am now

I think i could prove it by substituting n=(a,b,c), x0=(x0,y0,z0),... etc. and solving the two equations, but i'd prefer not to

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Re learning math from the ground up and stuck on a problem.

5/16 • 1/10 - 1/32

The answer is 0, but I got 40/5 for some retarded reason.

>how do i prove that the intersection of two distinct planes is a straight line?
You can not, since it is not true.

wtf
what's a counterexample?
post how you got 40/5

>wtf
>what's a counterexample?
Draw some pictures of planes.

What is did I get the Least common denominator of 16, 10 and 32 and got 160.

5•10 50/160

1•10 10/160

1•5. 5/160

Then I multiplied 10/160 • 50/160
And got 500/160.

500/160 - 5/160 and got 495/160
Simplified that and now I’m at 99/32.

It’s a different answer but I’m still fucking up

I'm not sure where the 50/160, 10/160 and 5/160 came from, but the answer is
[math] \dfrac{5}{16}\cdot\dfrac{1}{10}=\dfrac{5\cdot 1}{10\cdot 16}=\color{blue}{\dfrac{5}{160}} [/math]

and then

[math] \begin{align}\dfrac{5}{16}\cdot\dfrac{1}{10}-\dfrac{1}{32}&=\color{blue}{\dfrac{5}{160}}-\dfrac{1}{32}\\ &=\dfrac{5}{160}-\dfrac{5}{32\cdot 5}\\&=\dfrac{5}{160}-\dfrac{5}{160}\end{align} [/math]

What I did is just find the least common factor of the three numbers and multiplied the numerator and denominator respectively then multiplied and subtracted.

I’m not sure why I did that.

When you did

5/160 - 1/32 why did you multiply by 5 ?
What’s the meaning behind that

Another thing I did is that instead of just multiplying I looked for a common denominator.

I didn’t know you only do that when you’re adding and subtracting fractions.

You can only subtract terms if they have the same denominator. So i multiplied the denominator by 5 since 32*5=160. The fraction is still the same though since i just multiplied by 1:
[math]\dfrac{1}{32}=\dfrac{1}{32}\cdot 1=\dfrac{1}{32}\cdot\dfrac{5}{5}=\dfrac{5}{32\cdot 5}[/math]

nice. how do you make it blue?

Can somebody explain how to find a formula for (x^n-1)/(x-1)?

>Can somebody explain how to find a formula for (x^n-1)/(x-1)?
en.wikipedia.org/wiki/Polynomial_long_division

Ok, I'm not trying to be a brainlet right now, but I still can't figure it out, how do I deal with the exponent being n?

>Ok, I'm not trying to be a brainlet right now, but I still can't figure it out, how do I deal with the exponent being n?
en.wikipedia.org/wiki/Mathematical_induction

So induction would be used to do the division?

Try it with n = 1, 2, 3, etc until you notice a pattern, then assume it's true for a general n and show how that assumption leads to it being true for n + 1.

The potato paradox.

100lbs of potato if it is 98% water and 1% solid stuff and by mathematics removing 2% of the water would mean it would weigh 98 lbs right? No! If you try out the math by solving it it always ends up with 98.89898989...% and that is wrong. Instead the right answer is it would weigh 48lbs and that's because if you divide it the answer would be "exactly" 98%.

How does removing 2% of a mass decrease it's weight over 50%.

Pls explain

[eqn]\sum\limits_{i=1}^n i^{n-1} = x^{n-1}+x^{n-2}+...+x^2+x+1[/eqn], would this be right for the formula?

The right hand side looks good but does not correspond to what you've written on the left.

Thanks, I see the issue

HAVN'T SLEPT FOR 30 HOURS
WENT THROUGH 400 PAGES OF LINEAR ALGEBRA BOOK
2 LITERS OF ENERGY DRINKS CONSUMED

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You’ll forget it all for cramming

Why do we reduce to 9? Is this essentially just cross division to reduce to its lowest terms?

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You can rewrite the top as (9)*1*11/(9)*4*44, the 9s cancel each other out.

Not quite understanding you

[math]\left(\frac{9\cdot11}{44\cdot36}\right)=\left(\frac{9}{36}\cdot\frac{11}{44}\right)[/math]

But 9•11 is 99? I’m definitely missing something here sorry

[math]\frac{9}{36}=\frac{9}{9\left(4\right)}[/math]

I’m too retarded, I’ll figure it out eventually thanks though

Wait are you just flipping the denominators and then just dividing the numerator and denominator?

So I am finishing up Real Analysis and thinking about being a teacher's assistant next semester for calc, but I have never learned integration by parts and my teacher keeps asking questions that need it/ What is the single best way to learn it?

you can do all other types of integration??

Pretty much, I self-studied them, but I hated doing integration by parts so I didn't practice it enough to learn it well.

When it says the subsapce given by the equation, does it mean the orthogonal complement of the vector (1,1,1)? That's what I assumed and when I worked it out I ended up with nice numbers typical of a contrived example question but I have a feeling i've been going in the complete wrong direction. I'll post my working in a sec in case it helps anyone

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I'm a messy cunt sorry

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/a/ was able to make a cripple fucking simulator. What have you done with your life?

Would Veeky Forums be interested in working with some autists from /g/ to develop a FOSS android? We're talking from the ground up - motor skills, intelligence, human interaction, and human "interaction". We were thinking Veeky Forums could especially help with materials science, but volunteers with any knowledge/skills/ambition are welcome.

Does anyone know of any YouTube videos to help a brainlet learn this stuff? I really want to understand it

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What does it mean when a problem asks me to find the thermodynamic identity for a certain variable? I thought the thermodynamic identity was just dU = TdS - PdV.

About to finish my first two semesters for my 4 semesters MS (EE). I have the choice of a few internships over my subject at good companies or doing research at my university over the summer, should I just do the internship if I am not 100% on whether I want to pursue a PhD after my MS yet? I plan to go into industry whether I get an MS or PhD anyways.

What are some good freeware circuit drawing and/or simulation software for Mac OS X?
I tried Spice, which works fine for windows, but is absolute ass on Mac. No fucking icons, everything's done through keyboard shortcuts, and running a simulation is painful as all hell.
Any and all alternatives are welcome

Have ya tried Khan Academy?
khanacademy.org/math

Consider this:

[math]
\frac{2}{1} * \frac{1}{2} = 1
[/math]
essentially 2*1/2
so that's why we can simplify by reducing 2s

Shouldn't the directions on the middle spring be flipped? As in I push m to the right, middle spring is compressed; meanwhile push m2 to the right, resulting in a restoring force to the left in the middle spring

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If b is a power of a you have a problem.

You are correct. You are basically subtracting out the mean of x y and z, giving you three new numbers having zero mean

>Shouldn't the directions on the middle spring be flipped?
no, you could flip the direction of the arrows if you wanted to, but then you would also have to change the sign of the equation
> As in I push m to the right, middle spring is compressed; meanwhile push m2 to the right, resulting in a restoring force to the left in the middle spring
the spring is only ever going to push the masses apart or pull the masses together, it doesn't make any sense for the spring to be pushing one and pulling the other

>how do i prove that the intersection of two distinct planes is a straight line?
You don't. Consider the case in which the planes are the same, or the case in which they are parallel.

Without thinking about it, my guess is that you consider a system of linear equations which describe where the planes are.
From that you will conclude that, either they intersect everywhere, have a one dimensional solution set, or there is no solution.

what's the proper definition of a linear ODE?
i've seen a lot of definitions like it's an ODE where "all y terms appear in a linear manner", "all y terms appear to a power no higher than 1", etc., but they confuse me and don't seem particularly rigorous

So I've got a particle theory module at uni that frequently uses Einstein summation, the spacetime metric, spacetime vectors and things like that. But despite mentioning lowering and raising indices like
[eqn]V^\mu=\eta^{\mu\nu}V_\nu[/eqn][eqn]V_\mu=\eta_{\mu\nu}V^\nu[/eqn]
It is never explained what the difference is between the index being above or below. It's not really explained what its even called so I have no idea what to google/youtube to learn more. Apparently I might want to raise or lower the indices to help simplify equations but I have zero intuition as to when or why I might do this

I think I'm retarded, max is supposed to be a non-linear function, but using the usual proof of linearity, it keeps coming up as linear. Is max() not what I think it is?(the highest value of a matrix)

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surely the best way to prove this is to find a counter example?

It's just that I'm trying with different numbers and I'm getting the same result. Using max() on wolfram alpha also wields the same results, yet everywhere I see, they say that max() is nonlinear. As usual, I'm probably doing something wrong, and I don't know what.

>max is supposed to be a non-linear function
Why?

A subscript index is a covariant vector and a superscript is a contravariant vector.
They are different ways to discribe the same vector in non euclidean space.
You can read about it in every book about differential geometry and tensors, they will do a way better job explaining it than I could.

It isn't?

I got it, as usual, I'm dumb. the problem is that I kept using the same place to hold the highest number.

I read this article about the brain and it made me question a lot of things I assumed : aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer
Do you anons find any value in it? If yes do any of you know some literature that I could read to have an understanding of how the human brain really functions? Can be a thesis or a book, anything to know more if theoretically you'd want to create a true artificial intelligence for example.
I know we are far from knowing enough to achieve that but I'd like to know were science currently is on the subject

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So what you’re describing is cross cancellation?

[math]x_0=\gamma(0), x_\alpha^+=\gamma(\alpha), x_\alpha^-=\gamma(-\alpha)[/math], these three points define a circle, so you can write some equation and the center [math]c_\alpha[/math], then differentiate this equation and you get two zeroes, [math]y_1,y_2[/math], then differentiate again and you get a zero [math]z_0[/math], if [math]\alpha\rightarrow 0[/math] then all those points tend to [math]x_0[/math] and the equations tell you they satisfy exactly what you wanted in the limit, or something.
Been a while since I took differential geometry, often you just have to find the right equation and you get the result you want right away.

Well, the cross-cancellation is just a handy term but i dont think it is an actual thing.

Basically, if you multiple a number by X and then divide by X there is no point doing so, thus you can remove X's

Ahh thank you

hey a dumb physicist told me once that subzero temperatures (Celsius) are 'hot'. What did he mean by that??

What should I do if I am interested in CS but do not want to study baseline engineering?

What do you call this letter?

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detexify.kirelabs.org/

xi
(pronounced "zee")

Study CS without studying baseline engineering

Does this not belong in this thread ? Should I make another one just for this ?