Example 3.8.  Show that the function  [Graphics:Images/CauchyRiemannMod_gr_189.gif]  is differentiable for all [Graphics:Images/CauchyRiemannMod_gr_190.gif] and find its derivative.

Explore Solution 3.8.

Enter the function f[z] and determine if the Cauchy-Riemann equations hold.

[Graphics:../Images/CauchyRiemannMod_gr_199.gif]




[Graphics:../Images/CauchyRiemannMod_gr_200.gif]

 

 

The Cauchy-Riemann equations hold everywhere, so that  [Graphics:../Images/CauchyRiemannMod_gr_201.gif] is analytic for all values of  z.

[Graphics:../Images/CauchyRiemannMod_gr_202.gif]




[Graphics:../Images/CauchyRiemannMod_gr_203.gif]

 

 

Remark.  We can write this function as  [Graphics:../Images/CauchyRiemannMod_gr_204.gif],  and investigate  [Graphics:../Images/CauchyRiemannMod_gr_205.gif].  

[Graphics:../Images/CauchyRiemannMod_gr_206.gif]






[Graphics:../Images/CauchyRiemannMod_gr_207.gif]

We have shown that  [Graphics:../Images/CauchyRiemannMod_gr_208.gif] is differentiable and hence analytic for all z.

Remark.  [Graphics:../Images/CauchyRiemannMod_gr_209.gif]  is an entire function.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2006 John H. Mathews, Russell W. Howell