### It is an explanation of a theorem in radius of convergence of power series. ∞ ∞ Theorem:- ∑ anzn is a power series and ∑ nanzn - 1 is the power series obtained n=0 n=0 by differentiating the first series term by term. Then the derived series has the same radius of convergence as the original series.

Complex Variable Radius of Convergence of the Power Series