- #1

christianrhiley

- 4

- 0

## Homework Statement

Let {a_n} be a monotonically decreasing sequence of positive real numbers with lim a_n = 0. Show the radius of convergence of [tex]\sum[/tex]a_nx[tex]^{}n[/tex] is at least 1.

## The Attempt at a Solution

I have no real attempt at a solution since I'm unsure how to proceed. I've tried using the power series definition and using a fixed x_0, but I get nowhere using this method. Can someone outline how this proof might look? Thanks.