Example 6.25. Show
that
, where
C is the circle
with
positive orientation.
Explore Solution 6.25.
Enter the integrand
and
locate the singularities.
![[Graphics:../Images/IntegralRepresentationMod_gr_116.gif]](../Images/IntegralRepresentationMod_gr_116.gif)
Find the singularity that lie inside
.
![]()
Since z = i is a singularity of
order n = 4 , multiply the integrand by
to obtain the function f(z).
![[Graphics:../Images/IntegralRepresentationMod_gr_122.gif]](../Images/IntegralRepresentationMod_gr_122.gif)
Use Cauchy's Integral Formula for Derivatives to evaluate the
integral of
taken over C.
![[Graphics:../Images/IntegralRepresentationMod_gr_124.gif]](../Images/IntegralRepresentationMod_gr_124.gif)
![[Graphics:../Images/IntegralRepresentationMod_gr_125.gif]](../Images/IntegralRepresentationMod_gr_125.gif)
Thus, we have found the value of the contour integral.
![[Graphics:../Images/IntegralRepresentationMod_gr_127.gif]](../Images/IntegralRepresentationMod_gr_127.gif)
![[Graphics:../Images/IntegralRepresentationMod_gr_128.gif]](../Images/IntegralRepresentationMod_gr_128.gif)