University Calculus: Early Transcendentals (3rd Edition)

Published by Pearson
ISBN 10: 0321999584
ISBN 13: 978-0-32199-958-0

Chapter 9 - Section 9.5 - Absolute Convergence; The Ratio and Root Tests - Exercises - Page 516: 26

Answer

Diverges and $\lim\limits_{n \to \infty} a_n=\dfrac{1}{\sqrt [3] {e}}$

Work Step by Step

Consider $a_n=(1-\dfrac{1}{3n})^n$ Now, $\lim\limits_{n \to \infty} a_n=\lim\limits_{n \to \infty} (1-\dfrac{1}{3n})^n$ Thus, we have $=\lim\limits_{n \to \infty} (1+\dfrac{(-1/3)}{n})^n$ So, $\lim\limits_{n \to \infty} a_n=e^{-1/3}=\dfrac{1}{\sqrt [3] {e}}$ We need $\lim\limits_{n \to \infty} a_n =0$ for the series to converge, but we can see that $\lim\limits_{n \to \infty} a_n \ne 0$ Hence, The Series Diverges and $\lim\limits_{n \to \infty} a_n=\dfrac{1}{\sqrt [3] {e}}$
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.