The function is .
Find when
.
Theorem 7:
\If is a one to one differentiable function with inverse function
and
then the inverse function is differentiable at
and
.
Find .
By trail and error method, equate the value to .
Substitute in the function.
.
Therefore then
.
.
Apply derivative on each side with respect to .
Substitute then
.
then
.
.
.