(a). Use a graphing calculator or computer to graph the function f (x) = x4 – 3x2 – 6x2 + 7x + 30 in the viewing rectangle [-3, 5] by [-10, 50]. (b). Using the graph in part (a) to estimate slopes, make a rough sketch, by hand, of the graph of f'. (See Example 1 in Section 2.7.) (c). Calculate f'(x) and use this expression, with a graphing device, to graph f'. Compare with your sketch in part (b).