# Math Help - How to find r forthe sum of GP series?

1. ## How to find r forthe sum of GP series?

Hi

Given such an equation, how do I find r? Thank you

(1-r^m)/ (1-r)= 1000
where m can be any positive whole number
the right-hand side can also be any positive number

The equation is actually the summation for a GP series with a=1, so basically I want to know how to find r (ratio factor)for the sum of a GP

2. ## Re: How to find r forthe sum of GP series?

You need to have been told how many terms are in your series.

If m=181?
Thanks

4. ## Re: How to find r forthe sum of GP series?

Isn't there a general formula 4 different m & summation value?
Thanks