(a)

Observe the derivative graph:

Critical points are the points where the

\"\"

curve touches the $\"\"$ - axis.

From the graph the critical points are

\"\"

, $\"\"$ and $\"\"$ .

$\"\"$

(b)

Use first derivative test to identify all relative extrema.

$\"\"$ changes from positive to negative at $\"\"$ .

Therefore according to first derivative test , the function has maximum at $\"\"$ .

$\"\"$ changes from negative to positive at $\"\"$ .

Therefore according to first derivative test , the function has minimum at $\"\"$ .

But $\"\"$ not changes its sign at $\"\"$ .

So at $\"\"$ , the function has neither maximum nor minimum.

(a) Critical points are

\"\"

, $\"\"$ and $\"\"$ .

(b) Relative minimum at $\"\"$ .

Relative maximum at $\"\"$ .