you made the same mistake here...sort of. again, do the contrapositive. assume that x and y are not odd integers. that is, we have two cases, x and y are both even, or (without loss of generality) x is even and y is odd. what does that tell us about xy?2. If xy is an odd integer then x and y are odd integers.
Pf: Since xy is an odd integer then there exists some integer c so that xy = 2x+1.
Thats as far as I can get on either of those.
How are you with implications?