$\"\"$

The function is $\"\"$ .

Critical number :

A critical number of a function $\"\"$ is a number $\"\"$ in the domain of $\"\"$ such that either $\"\"$

or $\"\"$ does not exist.

Therefore, solutions of $\"\"$ are the critical numbers.

The function is $\"\"$ .

Differentiate $\"\"$ on each side with respect to $\"\"$ .

$\"\"$

To find the critical numbers, equate $\"\"$ to zero.

$\"\"$

Critical number of the function is $\"\"$ .

$\"\"$

$\"\"$ is a critical number of the function $\"\"$ .