[10 marks] Suppose that f is a metion such that ts] and f"[:3:] exist for an}.r real number 3:. Dene that g is a function with 903] : f'lf'} and 9(3) : f($},'55 for :1: 75 U. Given that 9(3) is continuous for an}.r real number I. Prove that 913:} exists for an}.r real number a\