/sqt/ - Stupid Question Thread

It has to be greater than 10 as 10^10 has 10 digits
Then AFAIK it's trial and error for 11 12 13 and 14

literally trivial, just write out what [A,BC] and [AB,C] are and you'll see the others pop out

put some effort in brainlet

What do you mean? The best way to learn mathematics is to be taught it by a good teacher. Second to that is a good book.

Software like matlab and mathematica are tools we use to help arrive at a solution.

I've tried that and it's not obvious to someone who's just learnt this how ABC - BCA is related to [A,B], [A,C], [B,C]

en.wikipedia.org/wiki/Commutator#Identities_.28ring_theory.29

ABC-BCA=ABC-BAC+BAC-BCA=[A,B]C+B[A,C]

Cheers, I nearly got that but got a sign wrong on one of the BACs so they didn't cancel

I am confused because I can't apply Lagranges Theorem to this problem [math] $ \langle 2 \rangle / \langle 8 \rangle \text{ where } \langle 8 \rangle \subseteq \langle 2 \rangle \subseteq \mathbb{Z} $ [/math] since G infinite. How should I approach this problem?

I forgot to state the problem :), the problem is to find the order of said quotient group.

= multiples of 2
= multiples of 8

so / = multiples of 2 mod 8 = {0,2,4,6} which has order 4

Can somebody tell me why Oct4 is relevant for the animal pole during embryo development?

>Cindy: zika virus is killing everyone!!
>Travis: nah b that's just what the media/facebook wants you to believe

>Cindy: bees are endangered!!
>Travis: yeah true we all fucked

So is the bee thing another phony fact or is it true? I tried googling it but couldn't find a definitive answer.

Bees are dying off to some degree, and the consequences of their extinction would be dire. How much their situation is really at the edge of a cliff is less clear. But it's not the kind of thing where you can afford to be careless and hope for the best so assuming the worst is the wiser option.

Mostly because for every force in the universe to be so exactly balanced as to cause no relative motion, every particle would need to be placed in an extremely ordered and uniform arrangement that would never come about naturally.

Small variations in density of the early universe led to clumps of matter forming massive 'webs' of galaxies given time for the gravity of the gas clouds to collapse themselves. The energy of the collapse plus the energy released by fusion of atoms in stars is what produced the potential for more complex small-scale motion that we observe.

Also quantum effects allow and indeed force very small particles to move, no thing can exist at absolute zero.

Zika virus behaving like the common cold is probably one of the spoopiest health crisis scenarios I can come up with, it'd be like Children of Men but instead of no babies there'd be a huge number of literal brainlet babies that we would have to deal with one way or another.

Is citing a textbook exercise to reference a mathematical fact considered to be in bad taste?

helb bis drainbet

First note that [math]a \equiv b \mod m \Longleftrightarrow a - b = km[/math] and [math]c \equiv d \mod m \Longleftrightarrow c - d = lm[/math] for [math]a,b,c,d,k,l,m \in \mathbb{N}[/math].
Then: [math]a + c = b + d + m(l+k) \Longleftrightarrow a+c \equiv b+d \mod m[/math].
Also: [math]ac = bd + m(dk + bi +m) \Longleftrightarrow ac \equiv bd \mod m[/math].

Anyone know of a good computer mathematics course available online? I bombed the final exam last year, and I'm hoping to catch up over the summer after retaking the intro course this semester.

yea i just got confused, i thought a triple equal b mod m is b = mk + a

sry for retardation

so i just had a midterm and one of the question was:

>if p and q are prime, then p + q is composite

so all i did was take p = 2 and q = 3, then we have p + q = 5 which is not composite

its a 6 marks question so im spooked a little now if im just not seeing something horribly obvious.

How do I know if a STEM field is right for me? What do I do when I find out it isn't?

I am very well aware that the equation of a line is: y - y1 = m (x - x1)

So if I wanted to build a f(t) based on pic related what I would need to do is get all the slopes, calculate the average then sum all X´s and Y´s, get their average too, and then that would be my function right?

Am I processing this correctly or am I just extremely dense?

When is L(A) considered regular and when is L(A) considered context-free?

I would've thought if L(A) is regular, it's automatically context-free because any regular language can be expressed using a CFG.

What's the difference in angular momentum equations for hoops and discs?

How do i do this ?
>math.stackexchange.com/questions/118832/how-are-3d-coordinates-transformed-to-2d-coordinates-that-can-be-displayed-on-th

I have a very basic math level and i don't understand most of the formulas here. Could anyone explain this process with easy words ?
Thanks

Anyone else feel like a master's is actually easier than a bachelor's? In my bachelor's studies, i had to fight through so many classes that were seemingly just there to "weed out" students, but now i feel like i can study what i really want and what i'm really interested in. the stuff is arguably more advanced and more complicated, but i don't mind because i'm genuinely interested in all of it

Are quantum computers basically what analog computers would be if not for the noise?

Well yeah if you're motivated it all comes easier. Good for you user

>Anyone else feel like a master's is actually easier than a bachelor's?
Everything is easier when you're 22-24.

no it's alright. if you follow the citation rules, you can cite almost everything.

You take a 3d objet and send it full force on a wall so that nothing bounces and stay exactly where it hit the wall.
In other words, you make a coordinate change so that your wall is a linear space, and then you project everything on it using a linear projector. Or maybe you can just use affine projector.

I've heard a story once that in some big math competition one of the contestants in order to save time wrote something like "the solution to this problem can be found in book X under section Y", and the committee qualified that answer, but changed the rules so that if the contestants wanted to do something like that again in the future, they would have to write the exact page number.

senpai plz answer me

If I have something like sin(5x^2) is there a way to quickly calculate the value without a unit circle or calculator?

Well surely p and q must not be 2

but 2 is a prime right? whats so wrong with that?

I am preparing for a test.
Pleas explain this to me.
I am at a loss.

There are many different interpolation algorithms.

If you wanted a single, linear function, you'd typically use a least-squares fit.

For a piecewise-linear function, you'd take the two points on either side of the independent variable and interpolate the line through the two points.

Higher-order functions (e.g. splines) use more points .

> I would've thought if L(A) is regular, it's automatically context-free
That's correct. Regular languages are a subset of context-free languages which are a subset of context-free languages which are a subset of all languages. Chomsky hierarchy.

if you are allowed 2, then the test setter made a booboo

khanacademy can be helpful for learning but it isn't really a full-fledged course

KhanAcademy is indeed very useful, but it aint gonna give me my math credit.

>without a unit circle
you don't need to keep any special hardware around for that shit user, you just remember some key values
if it isn't some easy key value and you don't have a calculator then you aren't gonna get a very exact answer though. before calculators people just looked these up in bigass tables printed on paper, so it's not like there's an easy way to calculate it by hand.
'course if all you want is a rough estimation you can just draw out a circle and try eyeballing it

you'll need to ask their school who they accept credits from then, since not all schools will accept all online classes.
in fact the school probably has some suggestions for online summer-school classes, if you ask them

I am, I am. They've got a two-day waiting list on replies though.

if it really said "+" and not "*" then it's trivially false, probably just a trick question and you answered right

I got that on a calculus 1 test (limits). We weren't allowed to use any calculators nor did we have the tables. As you say I guess I'll try to eyeball next time then...

alright, nice.

Did the test actually want a numerical answer?
In a non-calculator test they'd usually be perfectly happy with a response like "the answer is sin(45)"

>posting horizontally

i hope u fail dude i dont wanna break my neck.

I'm trying to figure out what is meant here when talking about alphabets. Is this a concatenation of an alphabet?

If it is, how do I define a concatenation of an alphabet? all possible strings of length 2? or is it just sigma*?
The alphabet is {a,b}

[math]\Sigma = \{a; b\}[/math]
[math] \Sigma^2 = \Sigma\Sigma = \{aa; ab; ba; bb\}[/math]

Why is Nozomi so fat?

Thanks.

how long, what is your experience ? dindunuffin

What degree should I go for if I want to build help build mechas like out of my japanese cartoons?
I'm 19 and applying for university this year probably to do maths because I don't know what I should pick, I feel like I should be doing engineering but not sure what kind, please help

Well I kinda gave an example from the top of my head, sorry. The actual task was:
Find the limit of (x^2tan(5x^2))/(sin(2x))^3 as x approaches 0.

Business studies, finance, law. Something that will help make you a millionaire. Because no-one else is going to pay you to make expensive-but-useless toys.

Why does mass exhibit the property of inertia?

ok, this really qualifies as a stupid question

can someone native in english help me to google this
>calculate the surface temperature at different layers within a cavity wall
so it actually provides useful links?

its mental that this is supposedly the easiest task of my course work, but its still driving me crazy

Serious answers only pls

Well that should be easily solvable without a calculator then. Sines cosines and tangents are all 0 or 1 around that area. You just needed a little help from your buddy L'hopital.

I mean...it should be just a simple application of fourier's law, no? Find your heat in/out and be carful with your control volumes/surfaces

> Find the limit of (x^2tan(5x^2))/(sin(2x))^3 as x approaches 0.
It's zero. And the slope is 5/8. Small-angle approximation.

As x->0:
sin(2x)->2x
tan(5x^2)->5x^2
(x^2*tan(5x^2))/(sin(2x))^3 -> 5x^4/8x^3 = 5x/8 -> 0

yeah, im fairly sure im doing something wrong, but I seriously cant say what

also I dont know how in gods name I should use fouriers law to calculate the surface temperature (read: the difference between the room temp and the wall surface temp [facing the room])

its funny because the rest of the course work (which should be way harder, was very easy for me lol)

Post more problem details and I'll see if I can help explain it in a reasonable way?

give me a sec, I'll draw something in paint

Fuck, that's actually so easy then. Thanks a lot, user.

alpha is the heat transfer coefficient (i for inside, o for outside)

1,5 is 1.5 (forgot that you guys handle that differently)

oh and this is how I tried to do it:
for the surface temp (inside)

t2 = 20 - (500*0,015)/(0,76*50) = 19,8°C

which is wrong, it should be 18,9°C

Where is that 500 W coming in/out?

Why does Veeky Forums substitute the word senpai for senpai?

Im not sure I understand your question but its the heat loss from inside to outside

calculated like this
q = k * delta T
q = 0,25 * (20-(-12))
q = 8 W/m^2
Q = 8 W/m^2 * 50 m^2 = oh fuck that no 500

well, it should 400 W, but even if, it doesnt change too much

20 - 40*0,015/0,76*50 = 19,8421

:/

Might be off, but i think you can get the idea. you use your known heat flux to find your surface temp and work inward from there.

Diagram wasn't copied for some reason

Doing an induction proof and fucking up the algebra.

When you have

(k^2+k)/2 + (2k+2)/2 why does this equal (k^2+3k+1)/2 vs (k^2+3k+2)/2

what is bernoulli's eqn useful for?
I have an exam tomorrow and I am going to fucking fail at this rate. Being addicted to this hellhole doesn't really help either

>(k^2+3k+2)/2
it equals this one because k^2+k+2k+2=k^2+3k+2

basically tells you how pressure and energy relate into each other, if you increase this then that decreases and blah blah blah, do some problems

alright, thanks

dont forget kPa is the SI unit for pressure and there is about 101.325 kPa in one atm

My book (Principles of Physics, Wiley) says its Pa though

weird, my book has this

its just a typo, especially since (k+1)(k+2)=k^2+3k+2

ok good, thanks i thought i was being retarded and having a crisis.

Take any 10 sequential positive whole numbers. Divide it in two non-empty sets A and B. Can there be such number sequence and such division that least common multiplier lcm(A) + lcm(B) = 2016?

I'm assuming there can't (I just think the exercise is not to just crunch numbers). I tried to look at parity, and some basic divisibility, got nowhere. The only maybe-useful thing I came up with is realisation that always at least one of the sets has lcm divisible by 10.

Any good book about determination of heavy metals in water?

Bonus point if there is a torrent of it

Progress update: the sums of lcms, seems if it ends in digits "016", the fourth least significant digit (a in "a016") will be odd. This is just a computed result (yay for Sage), that holds pretty high. Not sure why, any ideas?

fuck forgot about my question on here

thanks buddy, I'll report back if it worked :3

I get ya.

But is what I was doing correct in any way?