Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 10: Infinite Sequences and Series - Section 10.1 - Sequences - Exercises 10.1 - Page 570: 77

Answer

converges to $\dfrac{1}{2}$

Work Step by Step

Let $\lim\limits_{n \to \infty} a_n=\lim\limits_{n \to \infty} \dfrac{n^2 \sin (1/n)}{2n-1}$ But $ \lim\limits_{n \to \infty} \dfrac{n^2 \sin (1/n)}{2n-1}=\dfrac{0}{0}$ This shows that the limit has an Indeterminate form, so we will use L-Hospital's rule. This implies that $ \lim\limits_{n \to \infty} \dfrac{-\cos (1/n) \cdot (1/n^2)}{(-2n/n^2)+(2/n^3)}=\lim\limits_{n \to \infty} \dfrac{-\cos (1/n)}{-2+(2/n)}$ and, $\lim\limits_{n \to \infty} \dfrac{-\cos (1/n)}{-2+(2/n)}=\dfrac{1}{2}$ Thus, $\lim\limits_{n \to \infty} a_n=\dfrac{1}{2}$ and {$a_n$} converges to $\dfrac{1}{2}$.
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