If f : [a, b] → R is one-to-one, then there exists an inverse function f^{-1} defined on the range of f given by f^{-1}(y) = x where y = f(x). In Exercise 4.5.8 we saw that if f is continuous on [a, b], then f^{-1} is continuous on its domain. Let's add the assumption that f is differentiable on [a, b] with f'(x) ≠ 0 for all x ∈ [a, b]. Show f^{-1} is differentiable with (f^{-1})'(y) = 1/f'(x) where y = f(x).