$\"\"$

The function is $\"\"$ , $\"\"$ .

$\"\"$ at $\"\"$ , $\"\"$ .

Consider $\"\"$ .

Differentiate the function with respect to $\"\"$ .

$\"\"$

Again differentiate the function with respect to $\"\"$ .

$\"\"$

The zeros at $\"\"$ or $\"\"$ which is the condition on the first line.

$\"\"$

The given condition is satisfied, the function Increases at a maximum rate when $\"\"$ .