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
.
.
.