The function is  .

Apply derivative on each side with respect to x .

Apply the power rule: .

To find the critical numbers of , equate to zero.

Add 12 to each side .

Divide each side by 3 .

is out of the region .

Critical points in the given region is .

To find the absolute extreme of function in given region , sketch the function .

Critical point is minimum point over the interval .

Right end point is maximum point over the interval .

Minimum point is .

Maximum point is .