Hi,

I am having trouble with this one, please help if you can.

Let f:X ->Y be a function, Let A and B be subsets of X and let C and D be subsets of Y.

Prove that

f-1(C U D) = f-1(C) U f-1(D).

f-1(x) means the inverse function of some element x.

I know I need to start by saying,

Let x /in f-1(C U D)

and I think this means that there is some y /in f(C U D) such that f-1(y) = x.

But I am not sure on how to proceed. Any help is appreciated.