Repeat Problem 45 for f(x) = x cos2(x/3) on (0,10).
Let f(x) = sin x + cos(x/2) on the interval l = (- 2, 7).
(a) Draw the graph off on l.
(b) Use this graph to estimate where (x) < 0 on I.
(c) Use this graph to estimate where f"(x) < 0 on l.
(d) Plot the graph of f' to confirm your answer to part (b).
(e) Plot the graph of f" to confirm your answer to part (c).