Please answer parts C and D. Thank you!

Consider the following. F ( x ) = 2XV 16 - x2, [-4, 4] (a) Use a computer algebra system to differentiate the function. 4 ( x2 - 8) (-x2 + 16) 2 (b) Sketch the graphs of f and f' on the same set of coordinate axes over the given interval. 20 y 20 18 20 16 18 16 14 16 14 14 12 12 12 10 10 10 8 X - 3 - 2 -1 1 2 3 - 2 - 2 - 1 2 1 2 2 OPN -6 WebAssign Plot -8 -10 10 -12 -10 10 - 12 -14 - 12 -14 -14 -16 -16 -14 -16 -18 -16 -18 - 18 -20L 18 -20 -20 20 (c) Find the critical numbers of f in the open interval (-4, 4). (Enter your answers as a comma separated list.) X = (d) Find the open interval(s) on which f' is positive and the open interval(s) on which f' is negative. (Enter your answers using interval notation. ) positive negative