- #1

- 185

- 1

## Homework Statement

∞

Ʃ n / 2^n

n=1

## Homework Equations

ratio test

lim |a(n+1) / a(n)|

n->∞

## The Attempt at a Solution

I have the answer and the steps its just there's one part I am confused on,

first I just apply n+1 to all my n terms, which gives me,

∞

Ʃ [(n+1)/2^(n+1)] / [n/2^n]

n=1

and if I multiply the a(n+1) part by the reciprocal of an, I don't understand how the terms 2^(n+1) and 2^n cancel each other out and leaves me with just a 2?