7. Let ¢ be a function of bounded variation on [a, b] and 1> be its total variation function. Prove that if 1> is continuous at some point Xo E

(a, b), then ¢ is continuous at Xo. 00. This exercise is used in Section e14.4. If f is integrable on [a, b] and F(x) = IX f(t) dt prove that F is of bounded variation on [a, b].