Thread: Showing Analytic Using Derivative Equation

Need help please:

Suppose that F is analytic in a domain D. Define f by

f(z) = F(z) - F(zo)/ (z - zo)

if z ≠ zo and f(zo) = F'(zo), where zo is a point in D. Show that f is also analytic in domain D.

You can use the power series of .