/sqt/ Stupid Questions Thread

No idea how to do this. Any thoughts?

pathetic self-bump

Show that P(X > 0) is 1.

What do masters programs look for in people who have been in industry for a few years? What does a BS in engineering need to prove that they're competent for a MS in mathematics?

A brainlet explanation:
You have three terms, whose product equals to zero: (1-x)^(b-1), x^(a-1), and (a-a(a+b)x).
You know that one of them must be a zero, since the whole product is zero.

(1-x)^(b-1) can't be zero, since f(1) = 0.

x^(a-1) can't be zero, since f(0) = 0.

Therefore, (a - (a + b)x) must be the zero.

What's the clever way of solving this problem? I solved it using a fuck ton of trigonometry and algebra, but I'm retarded, so there has to be a better way.

P(X > s) = P(X > s | X > 0)

Is this how I prove that?

Sure you could do that. You could also let s = 0.

Surface of the sphere minus 6 caps, where the surface area of the cap can be found here:
en.wikipedia.org/wiki/Spherical_cap

It is really simple.
P(X0) = 1-P(X>0+t|X>t) = 1-P(X>t|X>t) = 1-1 = 0

Don't forget to add in the 6 disks.

Should I even start learning higher math when I'm bad at mental calculations?

Proofs don't require you to multiply 2 5-digit numbers in your head. You should be good.

All you need is logic and good abstract thinking.

>(1-x)^(b-1) can't be zero
Wrong.

>x^(a-1) can't be zero, since f(0) = 0.
Wrong.

So it's pointless as an adult to do basic multiplication and division with high numbers?

Wrong.

mentally?
yes
what are calculators for?

They're for weighing down papers

>So it's pointless as an adult to do basic multiplication and division with high numbers?
Yes, it is.
If you like it though, just do it. We all do pointless shit for fun.

solve this without a calculator.

How toxic is agricultural lime?
I live in the country and am surrounded by corn/beanfields. In an effort to get Veeky Forums I've started walking several miles per day on the dirt roads. The only problem is the farmers spread a bunch of lime a week or so ago. I looked up it's msds and read it's fairly nontoxic but the silica can cause lung problems. How long until I can safely resume walking them again? We've gotten a little moisture since they've spread it (maybe 1/4 inch all together). I eouldnt be as worried if it weren't so windy.

If you're that worried, why not just buy a cheap face mask?

Where can i download some free .dna or .prot files? i'm going to be working on SnapGene in a lab in a few weeks and i'd like some files to play around with to get a hang of this program before my training there

The teacher's answer is 14 choose 4 = 1001
but I can't seem to get that answer

Can anyone explain to me if I'm wrong, and if so, why?

>Should I even start learning higher math when I'm bad at mental calculations?
Doing calculations is irrelevant, that's what computers are for.
Nobody would spend his time calculating 123123123*231231231313-3233242 if a computer can do it in a billionth of that time.
I had classes were the professor did basic arithmetically mistakes and nobody cared.

Yes.

Is this a poisson process with lambda 4/3 or am I retarded

help

You write 25 as 1+1+...+1 (25 1's).
You put 5-1=4 bars in between so that they make 5 cells, each cell representing one of the x_i's.
Because you want at least 3 1's in each cell you just keep 5*3 1's aside and you put them after.
The problem reduces into having 25-3*5=10 1's and 4 bars and all you need is to choose the positions of the bars.

[math] \binom{(25-3 \cdot 5)+(5-1)}{5-1} = 1001 [/math]

Wait a minute. [math] \binom{14}{10} = \binom{14}{4} [/math] (you choose the positions of the 1's instead). You fucked up at the calculation.

The last post in the previous thread answered your question:

>Is this a poisson process with lambda 4/3 or am I retarded
The latter.
It says "the lifetime of a light bulb is exponentially distributed" and then it asks you questions about the lifetime of a lightbulb. It didn't ask what's the distribution of the number of dead lightbulbs after a certain time has passed.
T: the lifetime of a lightbulb (in years)
CDF of T is F(t):=1-e^( -1/4 x) [caveat: not sure if it is 1/4]
The answer to (a) is 1-F(2)
The answer to (b) is 1-F(1) because the exponential is memoryless. This obviously sounds retarded, but that's because T doesn't really follow an exponential distribution in practice.

Thanks for pointing that out to me.

If two vectors [math]\vec{a}[/math] and [math]\vec{b}[/math] are parallel, why does [math]||\vec{a}-\vec{b}||=\sqrt{a^2+b^2-2ab}[/math] and not simply [math]a-b[/math]?

>why does ||a⃗ −b⃗ ||=a2+b2−2ab
It doesn't. The thing on the right side of the equality is not defined (you can't square a vector).

Are you retarded? [math]\vec{a}^2=\vec{a}/cdot\vec{a}[/math], [math]||\vec{a}||=\sqrt{\vec{a}/cdot\vec{a}}[/math].

I meant [math]\vec{a} /cdot \vec{a}[/math].

Wtf? Fuck this gay ass site.

>Are you retarded? a⃗ 2=a⃗ /cdota⃗ , ||a⃗ ||=a⃗ /cdota⃗ −−−−−−√.
You can't square a vector, or divide vectors. Try rereading your textbook.

||a-b|| = sqrt((a-b)^2) = sqrt(a^2 + b2 - 2ab)

a2 = aa'

Kys.

Do you even understand what the things you write mean?

>||a-b|| = sqrt((a-b)^2) = sqrt(a^2 + b2 - 2ab)
You can't multiply vectors.

>Kys.
Nowhere on that page is a vector squared. Try rereading your textbook.

>You can't multiply vectors.
How about 1 by n matrices?

>How about 1 by n matrices?
What about them?

still can't

is there anything like factorials but for sums?

>is there anything like factorials but for sums?
en.wikipedia.org/wiki/Triangular_number

[1,1]^2 = [1,1][1,1]^T = 1*1 + 1*1 = 2. Huh, would you look at that.

>[1,1]^2 = [1,1][1,1]^T = 1*1 + 1*1 = 2. Huh, would you look at that.
You multiplied matrices, not vectors.

[1,1]^T is a n by 1 matrix, not 1 by n.

My dudes, I have realized my mistake. I apologize for my characteristically-Veeky Forums angst.

>If "A+B=C" and "B+A=D", what is "D-C"?
Am I retarded for not being about to figure this out?

>Am I retarded for not being about to figure this out?
Yes.

to be honest, yes

I don't get it, what's the answer here. It seems like an impossible question unless A and B have different values in the second equation.

D-C=B+A-(A+B)

That's not a real answer, though.
How are you suppose to figure what what the actual variables are?

[math]A+B=C \land B+A=D \longrightarrow D-C = (B+A) - (A+B) = B+A-A-B=0[/math].

>Am I retarded for not being about to figure this out?
Honestly? You should reconsider being a stripper.

Yeah, maybe. But I'm still fairly sure there's no actual numerical answer.

It's zero. Zero is a number.

Have different variables mean the same number doesn't make sense to me.

Having*

Different numbers can mean the same thing too:
1 + 2 = 3

What class could this possibly be for? Introduction to Pre-Remedial Babby Algebra?

I don't know, some friend I have just asked me over a text message. I doubt it's for a class.

56

>I'm asking for a friend hehe

Any help with 8.5.4c?

Use the method of characteristics.
[math] u_{tt} - c^2 u_{xx} = Q(x,t) [/math]
Therefore
[math] \frac{dx}{dt} = +/- c [/math]
and
[math] \xi = x + ct [/math]
[math] \eta = x - ct [/math]

Transforming the equation to the new coordinates,
[math] -4c^2 \frac{\partial^2 u}{\partial \eta \partial \xi} = Q(\xi,\eta) [\math]
Integrate along characteristic curves and enforce BCs

I study cs. I have this course that to pass you need to write an article of 10k words using latex. I can even "plagiarize" by translating articles from english . So my professor handed the topics to each student and I got to write about "Matrix logarithms". Where do I start ? I searched around the web and I don't know how I'm going to write 10k words about it. Is there any paper or part of a book that you have in mind and can recommend ?

there's no way that shit's getting graded, who's gonna read all that? Just put in random bullshit

What is the most intelligence species on earth after homo sapiens?

Homo Erectus

If there's a real neanderthal left in a cave somewhere probably them.

He proofreads a bit for possible google translate usage(some dumb dudes did it in the past). So far I'm thinking to get a chapter from a book + a paper.

I say structure it like this: paper, random bullshit, paper

Is, not was.

The world's a big place. I wouldn't be surprised if there's some left out in the bush.
Other options would be:
Octopus
Crows
Dolphins
Mushrooms

I’m a fucking pothead 18 year old with no scientific background who just lurks here because I find this board interesting and even I know you’re retarded.

>mfw row "15" (14) of Pascal's triangle, as expressed in base 10, contains 1001, 2002 and 3003 right next to each other like it ain't no thang and nobody's fucking with me

Not at all what I was implying. Might want to curb the autism so you can read social cues better.

It makes no sense to have different variables mean the same thing.

If there was no sense in it, then it would not have been asked. And if it wasn't asked, you would have never asked us and learned a lot!

Senseless things happen all the time.
Like you being born, for one.

What are Perfectoid Spaces?

>What are Perfectoid Spaces?
ams.org/notices/201409/rnoti-p1082.pdf

Can a head injury stop your heart?

I'm watching Death at a Funeral and a guy falls off a couch and smashes his head. A guy checks his pulse and concludes he's dead. I don't see how a hard hit to the head would stop the heart, was just wondering if it's possible or just a movie.

You do realize that your brain controls your heart, right?

The heart and lungs actually require the brain in order to function.

If you get hit in the head hard enough, your brain stem won't work and your heart will stop beating.