$\"\"$

The function is $\"\"$ .

Take logarithm of each side.

$\"\"$

Power property of logarithms : $\"\"$ .

$\"\"$

Apply derivative on each side with respect $\"\"$ .

$\"\"$

Product rule of derivative : $\"\"$ .

$\"\"$

Substitute $\"\"$ in the above equation.

$\"\"$ .

$\"\"$

$\"\"$ .