Solution 2.

Answer.   [Graphics:../Images/MobiusTranformationModHome_gr_38.gif].  

Solution.   Method I.   Use equations (10-13)  and  (10-14).  

(10-13)             [Graphics:../Images/MobiusTranformationModHome_gr_39.gif],

(10-14)             [Graphics:../Images/MobiusTranformationModHome_gr_40.gif].

Here we have  [Graphics:../Images/MobiusTranformationModHome_gr_41.gif]  and   [Graphics:../Images/MobiusTranformationModHome_gr_42.gif].  

Then  

            [Graphics:../Images/MobiusTranformationModHome_gr_43.gif]   

Therefore,   [Graphics:../Images/MobiusTranformationModHome_gr_44.gif].  

We are done.   

Solution.   Method II.   Use brute force and solve the equation  [Graphics:../Images/MobiusTranformationModHome_gr_45.gif]  for  z  and get

                    [Graphics:../Images/MobiusTranformationModHome_gr_46.gif]

Therefore,   [Graphics:../Images/MobiusTranformationModHome_gr_47.gif].  

We are really done.   

Aside.  We can let Mathematica double check our work.

[Graphics:../Images/MobiusTranformationModHome_gr_48.gif]

[Graphics:../Images/MobiusTranformationModHome_gr_49.gif]

[Graphics:../Images/MobiusTranformationModHome_gr_50.gif]

[Graphics:../Images/MobiusTranformationModHome_gr_51.gif]


[Graphics:../Images/MobiusTranformationModHome_gr_52.gif]

[Graphics:../Images/MobiusTranformationModHome_gr_53.gif]

We are really really done.   

Aside.  We can look at some graphs of the mapping  [Graphics:../Images/MobiusTranformationModHome_gr_54.gif].

                    [Graphics:../Images/MobiusTranformationModHome_gr_55.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_56.gif]

                    [Graphics:../Images/MobiusTranformationModHome_gr_57.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_58.gif]

               The image of the unit disk  [Graphics:../Images/MobiusTranformationModHome_gr_59.gif]  under  [Graphics:../Images/MobiusTranformationModHome_gr_60.gif]  is the right half plane  [Graphics:../Images/MobiusTranformationModHome_gr_61.gif].  
               You will be asked to show this in Exercise 10.

 

                    [Graphics:../Images/MobiusTranformationModHome_gr_62.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_63.gif]

                    [Graphics:../Images/MobiusTranformationModHome_gr_64.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_65.gif]

                    The image of the lower half plane  [Graphics:../Images/MobiusTranformationModHome_gr_66.gif]  under  [Graphics:../Images/MobiusTranformationModHome_gr_67.gif]  is the unit disk  [Graphics:../Images/MobiusTranformationModHome_gr_68.gif].  
                    You will be asked to show this in Exercise 11.

 

          [Graphics:../Images/MobiusTranformationModHome_gr_69.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_70.gif]

          [Graphics:../Images/MobiusTranformationModHome_gr_71.gif]          [Graphics:../Images/MobiusTranformationModHome_gr_72.gif]

                                        The image of the left half-plane  [Graphics:../Images/MobiusTranformationModHome_gr_73.gif]  under  [Graphics:../Images/MobiusTranformationModHome_gr_74.gif]  is the upper half-plane  [Graphics:../Images/MobiusTranformationModHome_gr_75.gif] .

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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