5. f (x) = sinx + 2x a) Use the Mean Value Theorem or Rolle's Theorem to demonstrate that f has at most one real root. ( A number c is a root of f when f (c) = 0) (4 points) b) Use the Intermediate Value Theorem to demonstrate that f has a real root in the interval [-It, 70] (4 points) c) How many roots does f have? (1 point)