(a)

Observe the derivative graph:

From the first derivative test if

\"\"

positive on the interval

\"\"

, then the function

\"\"

increases on the interval

\"\"

So the graph

\"\"

is increasing on

\"\"

since

\"\"

\"\"

The graph

\"\"

is decreasing on

\"\"

since

\"\"

\"\"

$\"\"$

(b)

Use first derivative test to identify all relative extrema.

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

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

(a) Increasing on

\"\"

Decreasing on

\"\"

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