Before I do that I'm going to post what I was just working on, I may be onto something with a direct proof (no pun intended). Any comments appreciated.
Let f: X -> Y and g: Y-> Z be functions so that g is ont-to-one and gof is onto. Let z\inZ. Since g is onto \existsy\inY such that g(y)=z...
Homework Statement
Let f: X\rightarrowY and g: Y\rightarrowZ be functions. Prove or disprove the following: if g\circf is onto and g is one-to-one then f is onto.
Homework Equations
N/A
The Attempt at a Solution
I'm honestly not sure what to do with this. I believe that the...