# 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 thereâ€™s an infinte amount of primes though.

Tim, you donâ€™t need to prove that thereâ€™s an infinite number of primes because there are infinite numbers, as a result there will be infinite primes.

Syntax, that wasnâ€™t what I was asking, but your proof is stupid. That doesnâ€™t follow logically at all.
Here are the proofs for that though: http://en.wikipedia.org/wiki/Euclid%27s_theorem

chagi, I tricked you. Thatâ€™s an unsolved problem in mathematics No one on Earth knows the answer.

Well that was mean.

Iâ€™ve learned some fun, applicable stuff in the last day! But itâ€™s a Calculus 2 class, so very few people would understand it.

â€¦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 thingâ€¦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.

Works fine for me. Itâ€™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 iâ€™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, iâ€™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 â€¦

All of the numbers added together make the next number.

Uhâ€¦ itâ€™s 2^x. (x >= 0, x % 1 = 0)

Try something more interesting, like 0, 0.693, 1.099, 1.386, 1.609â€¦

Whereâ€™s the expression?

I donâ€™t know what x % 1 = 0 means, but but thereâ€™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 canâ€™t solve your sequence, because Iâ€™m not too good with fractions.

Butâ€¦ I can make up problems for you guys to solve at leastâ€¦

Whatâ€™s the length of a side on a square with area of 200i, where i is the square root of -1?

Area canâ€™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 Iâ€™ll think about it in case itâ€™s a trick question.