# Math Help - Arithmetic / Geometric series HELP!

1. ## Arithmetic / Geometric series HELP!

Hi guys, i have 2 problems on arithmetic/geometric series. Any help would be appreciated!

1. Find x so that x-1, x, x+2 are consecutive terms of a geometric series.

2. Find: n $E$ k=1 (1+2k)

Thanks!!

2. Originally Posted by Dijakin
1. Find x so that x-1, x, x+2 are consecutive terms of a geometric series.
geometric series have a common ratio, so $\frac{x+2}{x} = \frac{x}{x-1}$