Contours and Contour Integrals

7 (c).  Evaluate  [Graphics:Images/ContourIntegralModHome_gr_415.gif].  (The minus sign in [Graphics:Images/ContourIntegralModHome_gr_416.gif] means the clockwise orientation.)

Solution 7 (c).

See text and/or instructor's solution manual.

Answer.   [Graphics:../Images/ContourIntegralModHome_gr_417.gif].  

                              [Graphics:../Images/ContourIntegralModHome_gr_418.gif]

                    The contour   [Graphics:../Images/ContourIntegralModHome_gr_419.gif]   for   [Graphics:../Images/ContourIntegralModHome_gr_420.gif].

Solution Method I.  The function is  [Graphics:../Images/ContourIntegralModHome_gr_421.gif]  and the curve is  [Graphics:../Images/ContourIntegralModHome_gr_422.gif]  for  [Graphics:../Images/ContourIntegralModHome_gr_423.gif]  and we obtain

                    [Graphics:../Images/ContourIntegralModHome_gr_424.gif]  and  [Graphics:../Images/ContourIntegralModHome_gr_425.gif],  
                    
                    then

                      [Graphics:../Images/ContourIntegralModHome_gr_426.gif]  

We are done.  

Solution Method II.  We could use a method that uses the following complex computations.

                    [Graphics:../Images/ContourIntegralModHome_gr_427.gif]

                    The contour   [Graphics:../Images/ContourIntegralModHome_gr_428.gif]   for   [Graphics:../Images/ContourIntegralModHome_gr_429.gif].

The function is  [Graphics:../Images/ContourIntegralModHome_gr_430.gif]  and the curve is  [Graphics:../Images/ContourIntegralModHome_gr_431.gif]  for  [Graphics:../Images/ContourIntegralModHome_gr_432.gif]  and we obtain

                    [Graphics:../Images/ContourIntegralModHome_gr_433.gif]  and  [Graphics:../Images/ContourIntegralModHome_gr_434.gif],  
                    
                    then

                     [Graphics:../Images/ContourIntegralModHome_gr_435.gif]  

We are really done.  

Aside.  After we have developed the Cauchy-Goursat Theorem in Section 6.3,

we will be able to use Corollary 6.1, [Graphics:../Images/ContourIntegralModHome_gr_436.gif],  

and we would immediately conclude that

                    [Graphics:../Images/ContourIntegralModHome_gr_437.gif].

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2008 John H. Mathews, Russell W. Howell