# Math

Every forum should have a math topic! Post mathemetical problems or such here!

Prove: There are an infinite number of prime numbers n such that n+2 is also a prime.

3 is one such prime, since 3+2 = 5, a prime number.
5 is one such prime, since 5+2 = 7, a prime number.
7 is not such a prime, because 7+2 = 9, a composite number.

GO

well screw you that was too hard I can proove that there’s an infinte amount of primes though. Tim, you don’t need to prove that there’s an infinite number of primes because there are infinite numbers, as a result there will be infinite primes.

Syntax, that wasn’t what I was asking, but your proof is stupid. That doesn’t follow logically at all.
Here are the proofs for that though: http://en.wikipedia.org/wiki/Euclid%27s_theorem

chagi, I tricked you. That’s an unsolved problem in mathematics No one on Earth knows the answer.

Well that was mean. I’ve learned some fun, applicable stuff in the last day! But it’s a Calculus 2 class, so very few people would understand it. …including this stuff (the latter half or so) and how to calculate the centroid of a region of uniform density and how to use that to calculate the volume of a solid of revolution of that region. (So basically, I can now calculate how much pressure the water in my swimming pool exerts on the pool itself, assuming all the walls are perfectly vertical and flat, and I can calculate the volume of something perfectly radially symmetrical, like a AA battery or the top portion of a water bottle! Woo hoo!) Not that these are realistic scenarios at all. Calculus is dumb when it comes to this sort of thing…you could get a better estimation of the volume of any object by submersing it in a liquid than by trying to figure out the equation that makes up its edges. link wont work Works fine for me. It’s for calculating the total force of a liquid on a vertical plate that is submersed in said liquid.

There was one man but the north Koreans thought he was a dog ate him.

woah
physics

yeah i’m only good at pura math

i would be good at physics
if i was taught physics
but i am not taught physics
and so, i’m not good at physics

k

create an expression for the n:th number in the following sequence:

1 1 2 4 8 16 32 64 …

All of the numbers added together make the next number.

Uh… it’s 2^x. (x >= 0, x % 1 = 0)

Try something more interesting, like 0, 0.693, 1.099, 1.386, 1.609…

Where’s the expression?

I don’t know what x % 1 = 0 means, but but there’s no zeroeth number. The first is a one the second is one, the third is two and so on.

% is the modulo operator in some programming languages. It pretty much just returns the remainder of the first number divided by the second, ie. 5 mod 1 = 0, 5.1 mod 1 = 0.1, 3 mod 5 = 2.

Oh, ok. Now, I can’t solve your sequence, because I’m not too good with fractions.

But… I can make up problems for you guys to solve at least…

What’s the length of a side on a square with area of 200i, where i is the square root of -1?

Area can’t be an imaginary number. Area has to be a non-negative real number.

what if you draw a square on the complex plane? ;D

My first instinct is just sqrt(200i) but I’ll think about it in case it’s a trick question.