Find the critical points and the interval on which the given function is increasing or decreasing, and apply the First Derivative Test to each critical point. Let
[math]

There are three critical points. If we call them [math] and [math], with [math], then
[math] =
[math] =
and [math] = .

Is [math] a maximum or minumum at the critical points?
At [math], [math] is
At [math], [math] is
At [math], [math] is

These three critical give us four intervals.
The left-most interval is , and on this interval [math] is while [math] is .
The next interval (going left to right) is . On this interval [math] is while [math] is .
Next is the interval . On this interval [math] is while [math] is .
Finally, the right-most interval is . On this interval [math] is while [math] is .