Calculus, 10th Edition (Anton)

Published by Wiley
ISBN 10: 0-47064-772-8
ISBN 13: 978-0-47064-772-1

Chapter 9 - Infinite Series - 9.6 Alternating Series; Absolute And Conditional Convergence - Exercises Set 9.6 - Page 646: 22

Answer

Absolutely convergent.

Work Step by Step

We test the series for absolute convergence by direct comparison. Since $\left| {\sin k} \right| \le 1$, it follows that $\mathop \sum \limits_{k = 1}^\infty \left| {\dfrac{{\sin k}}{{{k^3}}}} \right| \le \mathop \sum \limits_{k = 1}^\infty \dfrac{1}{{{k^3}}}$ Since the series $\mathop \sum \limits_{k = 1}^\infty \dfrac{1}{{{k^3}}}$ is a convergent $p$-series ($p = 3 \gt 1$), by the Direct Comparison Test, the series $\mathop \sum \limits_{k = 1}^\infty \left| {\dfrac{{\sin k}}{{{k^3}}}} \right|$ converges. Therefore, the series $\mathop \sum \limits_{k = 1}^\infty \dfrac{{\sin k}}{{{k^3}}}$ converges absolutely.
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