Visual Calculus - Derivatives and Graphs

Problem:
Draw the graphs of the function

f(x) = |x² - 1|

and its derivative on the closed interval [-2,2].

Visualization:

Using Maple:

> f:= x -> abs(x^2-1);

> df:= diff(f(x), x);

> plot({f(x),df(x)}, x=-2..2);