Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 11 - Infinite Series - 11.7 Taylor Series - Exercises - Page 590: 83

Answer

$\mathop {\lim }\limits_{x \to 0} \dfrac{{\sin x - x + \dfrac{{{x^3}}}{6}}}{{{x^5}}} = \dfrac{1}{{120}}$

Work Step by Step

From Table 2 we have $\sin x = \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{x^{2n + 1}}}}{{\left( {2n + 1} \right)!}} = x - \dfrac{{{x^3}}}{{3!}} + \dfrac{{{x^5}}}{{5!}} - \dfrac{{{x^7}}}{{7!}} + \cdot\cdot\cdot$, ${\ \ \ }$ converges for all $x$ Hence, the limit becomes $\mathop {\lim }\limits_{x \to 0} \dfrac{{\sin x - x + \dfrac{{{x^3}}}{6}}}{{{x^5}}} = \mathop {\lim }\limits_{x \to 0} \dfrac{{\dfrac{{{x^5}}}{{5!}} - \dfrac{{{x^7}}}{{7!}} + \cdot\cdot\cdot}}{{{x^5}}} = \mathop {\lim }\limits_{x \to 0} \left( {\dfrac{1}{{5!}} - \dfrac{{{x^2}}}{{7!}} + \cdot\cdot\cdot} \right)$ Thus, $\mathop {\lim }\limits_{x \to 0} \dfrac{{\sin x - x + \dfrac{{{x^3}}}{6}}}{{{x^5}}} = \dfrac{1}{{5!}} = \dfrac{1}{{120}}$.
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.