please solve

15. Given f (x) = (x-1) 3. f'(x)= 16. Use your calculator to graph f (x) and f'(x) in the following window: x : [-1.975, 1.975], y : [-2, 2]. Sketch below. 17. The relative maximum and minimum values of f (x) occur at x = 18. f' (x) = 0 or f'(x) is undefined at x = 19. f (x) is increasing on what interval(s)? 20. f' (x) is positive on what interval(s)? 21. f (x) is decreasing on what interval(s)? 22. f' (x) is negative on what interval(s)