(a)

The function is $\"\"$ .

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

$\"\"$

If $\"\"$ is a function , which is differentiable and $\"\"$ is an independent variable.

Then the differential $\"\"$ in terms of $\"\"$ is defined as $\"\"$ .

$\"\"$ .

(b)

The function is $\"\"$ .

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

$\"\"$

To get differential $\"\"$ , multiply both sides with $\"\"$ .

$\"\"$

(a) $\"\"$ .

(b) $\"\"$ .