# How do you find #S_n# for the geometric series #a_1=4#, r=0.5, n=8?

##### 2 Answers

Dec 6, 2016

#### Explanation:

there are two equations to find

if r is greater than 1, we use

and if r is less than 1, we use

in this question r is less than 1. so we use the second equation to find

therefore

Dec 6, 2016

#### Explanation:

Given an initial value

the

Using the given values (and a calculator)