# Math Help - product of two infinite series

1. ## product of two infinite series

Hello All,

suppose x and y are both between 0 and 1, I want to sum from 1 to infinity. Is there a nice way to express (in terms of a geometric series) the infinite sum of x^t times y^(t-1)? Thank you kindly for your help,

Sincerely,

Nick

2. Originally Posted by salohcin
Hello All,

suppose x and y are both between 0 and 1, I want to sum from 1 to infinity. Is there a nice way to express (in terms of a geometric series) the infinite sum of x^t times y^(t-1)? Thank you kindly for your help,

Sincerely,

Nick
Summation by parts may be what you need

CB