Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 11 - Infinite Sequences and Series - 11.1 Exercises - Page 725: 58

Answer

Sequence converges to $\pi$

Work Step by Step

$\lim\limits_{n \to \infty}a_{n}=\lim\limits_{n \to \infty}\sqrt n sin(\frac{\pi}{\sqrt n})$ $=\lim\limits_{n \to \infty}\frac{sin(\frac{\pi}{\sqrt n})}{\frac{1}{\sqrt n}}$ Substitute $\frac{1}{\sqrt n}=t$ When $nā†’\infty$, $\frac{1}{\sqrt n}ā†’0$ Therefore, $\lim\limits_{n \to \infty}\frac{sin(\frac{\pi}{\sqrt n})}{\frac{1}{\sqrt n}}=\lim\limits_{t \to 0}\frac{sin(\pi t)}{t}$ The limit is in the form $\frac{0}{0}$ Use L'Hospital's Rule $\lim\limits_{n \to \infty} a_{n}=\lim\limits_{t \to 0}\frac{\pi cos(\pi t)}{1}=\frac{\pi cos(0)}{1}=\pi$ Sequence converges to $\pi$
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.