Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning
ISBN 10: 1285741552
ISBN 13: 978-1-28574-155-0

Chapter 11 - Section 11.2 - Series - 11.2 Exercises - Page 716: 23

Answer

Converges and its sum is $\frac{1}{7}$ .

Work Step by Step

Since the given series is in the same form as the definition of the geometric series that can be found in page 750 definition 4 (except for the power of $r$ being n instead of $n-1$). The summation of an infinite geometric series is $S= \frac{a}{1-r}$ if |$r$| $\lt 1 $ , here $r$ is the common ratio of the geometric series. Now, If we choose n = 1 we can see that the initial term $a$ = $\frac{1}{4}$ and the common ratio $r$ = $\frac{-3}{4}$ (Dividing any latter term by its former we can get the common ratio). $r$ = |$\frac{-3}{4}$| $\lt 1 $ , which means the series is convergent. Now we only substitute in $S= \frac{a}{1-r}$. $S= \frac{\frac{1}{4}}{1-\frac{-3}{4}}$ = $S= \frac{\frac{1}{4}}{\frac{7}{4}}$ = $\frac{1}{7}$ . Hence, the geometric series converges and its sum is $\frac{1}{7}$ .
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.