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
There are three critical points. If we call them and , with , then = = and = .
Is a maximum or minumum at the critical points? At , is ? Local Max Local Min Neither At , is ? Local Max Local Min Neither At , is ? Local Max Local Min Neither
These three critical give us four intervals. The left-most interval is , and on this interval is ? Increasing Decreasing while is ? Positive Negative . The next interval (going left to right) is . On this interval is ? Increasing Decreasing while is ? Positive Negative . Next is the interval . On this interval is ? Increasing Decreasing while is ? Positive Negative . Finally, the right-most interval is . On this interval is ? Increasing Decreasing while is ? Positive Negative .
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