# Search results

1. ### How can B be an element of C?

Question 2 (a) how is it possible? B is a set (since A is a set), how can a set be an element of another set? Rather than saying: B is an element of C I thought it would be better to say: B is a subset of C. Also, can someone explain question 2 (d) to me? thanks
2. ### What exactly is a 2nd order differential equation?

A first order DE models the rate of change, e.g. when decay is proportional to time we have the DE: dM/dt = -K.M; this is describing that rate of change mathematically. Am I correct in saying that a 2nd order DE describes the rate of rate of change? Also, can anyone explain any application of...
3. ### STEP question, I don't know what it is asking

question 5. I am stuck on the last sentence. Please don't tell me what to do, just what they mean.
4. ### Can you help me choose my maths options?

I am studying Discrete Mathematics and if I do a PhD I would like to base the research on or around quantum computation. Unfortunately I can't take any physics modules at all, so please ignore the physics modules on the pages; I can only pick from the maths modules...
5. ### Can you check my proof by induction?

1 = 1 1 - 2^2 = -(1+2) 1 - 2^2 + 3^2 = (1+2+3) 1^2 - 2^2 + 3^2 - 4^2 = -(1+2+3+4) and so on. I have to prove that this relationship is true for all natural numbers. This is what I did: clearly it is true for 1, 2, 3 and 4. assume true for n odd: 1^2 - 2^2 + 3^2 - 4^2 ... + n^2 = (1 + 2 + +3...