Suppose g is a function from A to B and f is a function from B to C.
a) What’s the domain of f ○ g? What’s the codomain of f ○ g?
b) Suppose both f and g are one-to-one. Prove that f ○ g is also one-to-one.
c) Suppose both f and g are onto. Prove that f ○ g is also onto.
