View Single Post
Apr10-12, 11:06 AM
We need to show that g(f(a)) = g(f(b)) ==> a = b holds true for all a, b in A.
No, you don't need to show that, that's given.
You need to show that f is an injection. That is: f(a)=f(b) ==> a=b. That is what you need to show.