1. The problem statement, all variables and given/known data Prove that the following four statements are equivalent: (a) n2 is odd. (b) 1 − n is even. (c) n2 is odd. (d) n2 + 1 is even. 2. Relevant equations None really, just the use of different proofs ( indirect, etc...) 3. The attempt at a solution I'm having trouble with this one because of (2) things. First, the question makes no sense ( unless I'm reading it wrong) because, as I understand it now, it is asking to prove all statements are equivalent BUT 2 of them are eve and the rest is odd. Secondly, I'm having trouble with it because of the definition that n=2k is EVEN and n=2k+1 is odd because I tried this: Supposle n is odd. n=2k therefore n=(2k)2= 22k2 = 2(2k2) which goes against the definition. Can anyone point me in the right direction?