Exercise 5.6.6. [Used in Theorem 5.7.4.] Let [a,b] R be a non-degenerate closed bounded interval, and let f : [a,b] R be a function. Suppose that f is integrable and f has an antiderivative. Let F : [a,b] R be an antiderivative of f. Prove that if s,t [a,b], then