Exercise 2.  Determine where the following functions are continuous.

2 (c).  [Graphics:Images/ComplexFunLimitModHome_gr_96.gif].  

Solution 2 (c).

See text and/or instructor's solution manual.

Answer.  Continuous everywhere except at  [Graphics:../Images/ComplexFunLimitModHome_gr_97.gif].

Solution.  [Graphics:../Images/ComplexFunLimitModHome_gr_98.gif]  and the denominator is seen to be zero when  [Graphics:../Images/ComplexFunLimitModHome_gr_99.gif].   

Both  [Graphics:../Images/ComplexFunLimitModHome_gr_100.gif] and [Graphics:../Images/ComplexFunLimitModHome_gr_101.gif]  are continuous for all z and   [Graphics:../Images/ComplexFunLimitModHome_gr_102.gif]  when  [Graphics:../Images/ComplexFunLimitModHome_gr_103.gif].   

Therefore, by Theorem 2.4 the quotient  [Graphics:../Images/ComplexFunLimitModHome_gr_104.gif]  is continuous for all z except at  [Graphics:../Images/ComplexFunLimitModHome_gr_105.gif].  

Remark.  Later, using Definition 7.5, it will be seen that  [Graphics:../Images/ComplexFunLimitModHome_gr_106.gif]  is a removable singularity.

We are done.   

Aside.  We can let Mathematica double check our work.

[Graphics:../Images/ComplexFunLimitModHome_gr_107.gif]

[Graphics:../Images/ComplexFunLimitModHome_gr_108.gif]


[Graphics:../Images/ComplexFunLimitModHome_gr_109.gif]

[Graphics:../Images/ComplexFunLimitModHome_gr_110.gif]

Remark.  Later, using Definition 7.5, it will be seen that  [Graphics:../Images/ComplexFunLimitModHome_gr_111.gif]  is a removable singularity, and it's value will be  [Graphics:../Images/ComplexFunLimitModHome_gr_112.gif].

[Graphics:../Images/ComplexFunLimitModHome_gr_113.gif]

[Graphics:../Images/ComplexFunLimitModHome_gr_114.gif]


[Graphics:../Images/ComplexFunLimitModHome_gr_115.gif]

[Graphics:../Images/ComplexFunLimitModHome_gr_116.gif]


[Graphics:../Images/ComplexFunLimitModHome_gr_117.gif]

[Graphics:../Images/ComplexFunLimitModHome_gr_118.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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