Consider the following function f: R ----> R defined by f(x) = x3 + 1 .
(a) Note the contrapositive of the definition of one-to-one function given is: if a != b then f(a) != f(b). As we know, the contrapositive is equivalent to (another way of saying) the definition of one-to-one. Use the contrapositive to explain (no proof necessary) that f is a one-to-one function.