Hey, I don't know how to prove this.

So... help me (Bow)

Let f: X -> Y and g: Y -> X be functions so that g o f = 1x(which means Identity function). Prove that f is injective and g is surjective. Need either be bijective?

On hints sheet, This has 3 parts. Justify your answer to last part w/ a proof or counterexample.

Thank you