### Home > CALC > Chapter 10 > Lesson 10.1.2 > Problem10-9

10-9.

For each of the following series, decide if there is a finite sum. Then predict the sum. If there is not a finite sum, explain why.

1. $5 + 10 + 15 + 20 + …$

For an infinite geometric series:

1. $0.1 + 0.01 + 0.001 + 0.0001 + …$

1. $4 + \frac { 4 } { 3 } + \frac { 4 } { 9 } + \frac { 4 } { 27 } + \dots$

But $r$ must be _____.

The series in part (a) is arithmetic.
The other series are geometric. What is the value of $r$ in each case?

1. $2 − 2 + 2 − 2 + …$