If f . g and f are dill differentiable at a? 16. (a) Prove that if f is differentiable at a, then If | is also differentiable at a, provided that f (a) # 0. (b) Give a counterexample if f(a) = 0. (c) Prove that if f and g are differentiable at a, then the functions g (a). max(f, g) and min(f, g) are differentiable at a, provided that f(a) (d) Give a counterexample if f (a) = 8(a). all values, and fog