The function f is differentiable on the indicated interval. The table shows f′(x) for selected values of x.

(a) Sketch the graph of f,

(b) Approximate the critical numbers, and

(c) Identify the relative extrema.

f is differentiable on [−1, 1].

X f'(x) -10 X - 1 -0.75 -0.50 -3.2 -0.5 f'(x) 0.25 0.50 3.6 -0.2 0.75 -6.7 -0.25 0.8 1 - 20.1 0 5.6