9. Suppose that f : [-1, 1] -+ (0, co) is an even, continuous function such that f(x) dx = 1; -1 . f(x) is strictly increasing over [-1, 0]. (a) Show that f(x) attains its global maximum at 0. (b) Let G (r ) = [ s ( * ) dx . Use first principles to show that G(r) is differentiable over [-1, 1] and find its derivative