# Search results

1. ### Understanding separable ODES

Thank you Mark!
2. ### Understanding separable ODES

Yes I can do that. But I do not understand how do integrate (what word do I use?) ∫di(t)/i(t)
3. ### Understanding separable ODES

I understand how to integrate this: ∫y2dy. I don't understand how to integrate this: di(t)/dt = i(t)p(t) intergrate((di(t)/dt/i(t))*dt = p(t)dt) (see this image: http://i.imgur.com/OdKI309.png) how do you perform the intergral on the left, seeing as as it not dt, but di(t)? thanks
4. ### Capacitors/inductors have memory?

Hello, my textbook states that "Circuits that contain capacitors and/or inductors have memory". In what sense do they have memory? my understanding of memory, is retaining value. how do inductors/capacitors retain value? thanks daniel
5. ### F I pinch hold a book, with 6N on either side

If I pinch hold a book, with 6N on either side why is there only one force, of 6 Newton on the free body diagram? for example, the book has this free body diagram. http://i.imgur.com/pwtFZB6.png there are two forces applied to each side of the book. so why is it, than in the free body diagram...
6. ### Why is the area under a curve the integral?

here is a geometric proof, similar to the one in my textbook (copied from Aryabhata, from http://math.stackexchange.com/questions/15294/why-is-the-area-under-a-curve-the-integral) : Is this saying: that the A' equals the function. Which is implying, that the integration of A equals F (where F...
7. ### Prove that the square of any integer, when divided by 3. only by odd and even.

sorry mate. Prove that the square of any integer, when divided by 3, leaves remainder 0 or 1 but never 2. thanks
8. ### Prove that the square of any integer, when divided by 3. only by odd and even.

Homework Statement I know you could prove this by stating every integer is either 3m, 3m+1 or 3m+2. However I am trying to prove this just using either even numbers or odd numbers. so for example, when I try: (2x+1)^2 = 4x^2 + 4x + 1 - expand = 3x^2 + x^2 + 3x + x + 1 - group like...
9. ### Proving a floor function

Homework Statement Ok, So I've tried to prove this statement unsuccessfully. how would you guys do it? (assume [] means floor) [x-1][x+1]+1 = ([x])^2
10. ### If w is an even integer, then w^2 - 1 is not a prime number.

hello, I am trying to solve this problem: If w is an even integer, then w^2 - 1 is not a prime number. my current working. prove by contradiction If w is a even integer then w^2 -1 is a prime number. if w = 2x then w^{2} -1 = 4x^{2} -1 I am not sure where to go from here, maybe congruence...
11. ### Discrete math - proof of divisibility question

is this true or false: If a|b and a|c, then one (or both) of b|c or c|b holds. if I want to disprove this, can I: let a = 5, x = 2 and y = 3. b=ax c=ay then c=bz and c = bg doesn't hold.