1. ## Injection/Surjection

Let f : A -> B and g : B -> C be two functions.
(a) If g o f is injective, must g be injective ? Give a proof or a counterexample.
(b) If g o f is injective, must f be injective ? Give a proof or a counterexample.

a) So here's what I think i'm doing im not sure if it's right

if g o f is injective then there exists
x in g o f such that, x1 = x2
(g(f(x1)) = (g(f(x2))

but i cant go to g(x1) = g(x2) cus i dont know if f isinjective so I dont know how to continue b I start the same way but i get stuck again

2. Second question of the pdf file.