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 .
.
Substitute in above equation.
is clearly root of the equation.
Therefore then
.
Consider .
Differentiate on each side with respect to .
.
\
Power rule of derivatives : .
From theorem 7, .
Substitute in above equation.
.
.