# what is the radius of convergence of the power series when an is given as

• November 24th 2011, 02:36 AM
sorv1986
what is the radius of convergence of the power series when an is given as
what is the radius of convergence of the power series Σan xⁿ, where

a0=1, ,2<= |an| <= 3 for all n>=1 ?

regards. thanx in advance.
• November 24th 2011, 03:31 AM
FernandoRevilla
Re: what is the radius of convergence of the power series when an is given as
Quote:

Originally Posted by sorv1986
what is the radius of convergence of the power series Σan xⁿ, where a0=1, ,2<= |an| <= 3 for all n>=1 ?

Hint : $1=\limsup \sqrt[n]{2}\leq \limsup \sqrt[n]{|a_n|}\leq \limsup \sqrt[n]{3}=1$
• November 24th 2011, 03:50 AM
sorv1986
Re: what is the radius of convergence of the power series when an is given as
Thanks a lot.@fernando