7 (e).  Evaluate  [Graphics:Images/ContourIntegralModHome_gr_460.gif],  where C is the portion of  [Graphics:Images/ContourIntegralModHome_gr_461.gif]  in the first quadrant.

Solution 7 (e).

See text and/or instructor's solution manual.

Answer.   [Graphics:../Images/ContourIntegralModHome_gr_462.gif].  

                         [Graphics:../Images/ContourIntegralModHome_gr_463.gif]

                    The contour   [Graphics:../Images/ContourIntegralModHome_gr_464.gif]   for   [Graphics:../Images/ContourIntegralModHome_gr_465.gif].

Solution Method I.  The function is  [Graphics:../Images/ContourIntegralModHome_gr_466.gif]  and the curve is  [Graphics:../Images/ContourIntegralModHome_gr_467.gif]   for  [Graphics:../Images/ContourIntegralModHome_gr_468.gif]  and we obtain

                     [Graphics:../Images/ContourIntegralModHome_gr_469.gif]  and  [Graphics:../Images/ContourIntegralModHome_gr_470.gif],  
                     
                    then

                     [Graphics:../Images/ContourIntegralModHome_gr_471.gif]  

The last two real integrals are computed using

                    [Graphics:../Images/ContourIntegralModHome_gr_472.gif]  
                    
                    
                    and
                    

                    [Graphics:../Images/ContourIntegralModHome_gr_473.gif]  

We are done.  

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

                    [Graphics:../Images/ContourIntegralModHome_gr_474.gif]

                    The contour   [Graphics:../Images/ContourIntegralModHome_gr_475.gif]   for   [Graphics:../Images/ContourIntegralModHome_gr_476.gif].

The function is  [Graphics:../Images/ContourIntegralModHome_gr_477.gif]  and the curve is  [Graphics:../Images/ContourIntegralModHome_gr_478.gif]  for  [Graphics:../Images/ContourIntegralModHome_gr_479.gif]  and we obtain

                    [Graphics:../Images/ContourIntegralModHome_gr_480.gif]  and  [Graphics:../Images/ContourIntegralModHome_gr_481.gif],  
                    
                    then

                     [Graphics:../Images/ContourIntegralModHome_gr_482.gif]  

Here we have used the calculations indicated by equation (6-8) in Section 6.1:

                    [Graphics:../Images/ContourIntegralModHome_gr_483.gif]   

We are really done.  

Aside.  After we have developed the Cauchy-Goursat Theorem in Section 6.3 and the Fundamental Theorem of Calculus in Section 6.4

we will be able to compute the integral in an easy fashion:

                    [Graphics:../Images/ContourIntegralModHome_gr_484.gif]

We are really really done.   

Aside.  We can let Mathematica double check our work.

[Graphics:../Images/ContourIntegralModHome_gr_485.gif]

[Graphics:../Images/ContourIntegralModHome_gr_486.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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