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 771: 12

Answer

Convergent

Work Step by Step

The Comparison Test states that the p-series $\sum_{n=1}^{\infty}\frac{1}{n^{p}}$ is convergent if $p\gt 1$ and divergent if $p\leq 1$. $\Sigma _{k=1}^{\infty}\frac{(2k-1)(k^{2}-1)}{(k+1)(k^{2}+4)^{4}} \lt \Sigma _{k=1}^{\infty}\frac{(2k)(k^{2})}{(k+1)(k^{2}+4)^{4}}\lt \Sigma _{k=1}^{\infty}\frac{2k(k^{2})}{k(k^{2})^{2}} $ Note that $\Sigma _{k=1}^{\infty}\frac{2k(k^{2})}{k(k^{2})^{2}}=\Sigma _{k=1}^{\infty}\frac{2k^{2}}{k^{5}} =2\Sigma _{k=1}^{\infty}\frac{1}{k^{2}} $ We find that the series is a p-series with $p=2 \gt 1$ , which is converging and we know that, a series less than converging series is also converging.
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