The function is and
.
Find .
Theorem 7:
\If is a one to one differentiable function with inverse function
and
then the inverse function is
differentiable at and
.
Find :
Equate the function to .
By using inspection method find value of .
Substitute in above equation.
is clearly root of the equation.
Therefore then
.
Consider .
Apply derivative on each side with respect to .
From theorem 7, .
Substitute in above equation.
.
.