I need to prove or disprove the following: Z = integers
If x,y ÎZ, with x=2q and y=2h+1, for some q,hÎZ, then $uÎZ such that xy=2u+1
It seems like existential instantiation is the only way to do this. I don't know how to show it. Can I simply let h = u since addition and multiplication are closed under Z?