Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 11 - Infinite Sequences and Series - 11.4 The Comparison Tests - 11.4 Exercises - Page 772: 43

Answer

$\Sigma a_{n}$ is divergent.

Work Step by Step

Given that $a_{n}\gt 0$ , therefore, we can apply limit comparison test with $b_{n}=\frac{1}{n}$ Since, $\Sigma_{n=0}^{\infty}b_{n}=\Sigma_{n=0}^{\infty}\frac{1}{n}$ diverges If $\lim\limits_{n\to \infty}\frac{a_{n}}{b_{n}}\ne 0$ Then according to limit comparison test $\Sigma_{n=0}^{\infty}a_{n}$ will also diverge. $\lim\limits_{n\to \infty}\frac{a_{n}}{b_{n}}=\lim\limits_{n\to \infty}\frac{a_{n}}{1/n}=\lim\limits_{n\to \infty}na_{n}$ $\ne 0$ Hence, $\Sigma a_{n}$ is divergent.
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