Hi everyone,

I need some help on an exercise because i didn't really understand how to prove a statement like this :

let E and F be two sets and let $\displaystyle f$ be a map from E to F. Let A and A' be two subsets of E. Let B and B' be two subsets of F.

$\displaystyle f$(AUA')=($\displaystyle f$(A)U$\displaystyle f$(A'))

Can you please help me please? I know I have to demonstrate it but I don't know how...

Thanks a lot