Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 12 - Sequences; Induction; the Binomial Theorem - Chapter Review - Review Exercises - Page 839: 22

Answer

Converges, sum: $\frac{9}{2}$

Work Step by Step

An infinite geometric series converges if and only if $|r|\lt1$, where $r$ is the common ratio. If it converges, then it equals $\frac{a_1}{1-r}$ where $a_1$ is the first term. The common ratio is the quotient of two consecutive terms: $r=\frac{a_2}{a_1}=\dfrac{1}{3}=\frac{1}{3}$, $|\frac{1}{3}|\lt1$, thus it converges. Hence the sum (since $a_1=1$): $\dfrac{3}{1-\frac{1}{3}}=\frac{9}{2}$
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