Hello,

If a|b, then b=ka

square both sides =)

If n is even, then n=2n' ---> nČ=...2.Prove: for all n ϵ Z, n is odd if and only if nČ is odd.

If n is odd, then n=2n'+1 ---> nČ=...

3.using the definition of equal sets and the definition of subset, prove this

form of DeMorgan's Law:____ _ _

If A and B are sets then AUB=A∩B

This may be all you need eh ?