Exercise 9.  Limits involving  [Graphics:Images/ComplexFunReciprocalModHome_gr_378.gif].  

The function  [Graphics:Images/ComplexFunReciprocalModHome_gr_379.gif]   is said to have the limit  L  as  z  approaches  [Graphics:Images/ComplexFunReciprocalModHome_gr_380.gif],  and we write  [Graphics:Images/ComplexFunReciprocalModHome_gr_381.gif]  iff
for every  [Graphics:Images/ComplexFunReciprocalModHome_gr_382.gif]  there exists an  [Graphics:Images/ComplexFunReciprocalModHome_gr_383.gif]  such that  [Graphics:Images/ComplexFunReciprocalModHome_gr_384.gif]  (i.e., [Graphics:Images/ComplexFunReciprocalModHome_gr_385.gif])  whenever  [Graphics:Images/ComplexFunReciprocalModHome_gr_386.gif].  

Likewise,  [Graphics:Images/ComplexFunReciprocalModHome_gr_387.gif]  iff   for every  [Graphics:Images/ComplexFunReciprocalModHome_gr_388.gif]  there exists  [Graphics:Images/ComplexFunReciprocalModHome_gr_389.gif]  such that  
[Graphics:Images/ComplexFunReciprocalModHome_gr_390.gif]  whenever  [Graphics:Images/ComplexFunReciprocalModHome_gr_391.gif]  (i.e., [Graphics:Images/ComplexFunReciprocalModHome_gr_392.gif]).

Use this definition to  

9 (b).  Show that  [Graphics:Images/ComplexFunReciprocalModHome_gr_402.gif].  

Solution 9 (b).

See text and/or instructor's solution manual.

Solution.  Let  [Graphics:../Images/ComplexFunReciprocalModHome_gr_403.gif]  be given.    

Choose  [Graphics:../Images/ComplexFunReciprocalModHome_gr_404.gif].  

Suppose  [Graphics:../Images/ComplexFunReciprocalModHome_gr_405.gif].  

Then  [Graphics:../Images/ComplexFunReciprocalModHome_gr_406.gif],  so  [Graphics:../Images/ComplexFunReciprocalModHome_gr_407.gif]  whenever  [Graphics:../Images/ComplexFunReciprocalModHome_gr_408.gif].

Therefore,  [Graphics:../Images/ComplexFunReciprocalModHome_gr_409.gif].  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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