Draw the graph of f(x) = x3 - 4x2 + 3 and its derivative f'(x) on the

Question:

Draw the graph of f(x) = x3 - 4x2 + 3 and its derivative f'(x) on the interval [- 2, 5] using the same axes.
(a) Where on this interval is f'(x) < 0?
(b) Where on this interval is f(x) decreasing as x increasing?
(c) Make a conjecture. Experiment with other intervals and other functions to support this conjecture.