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 589: 54

Answer

$\mathop \smallint \limits_0^x \dfrac{{t - \sin t}}{t}{\rm{d}}t = \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{x^{2n + 3}}}}{{\left( {2n + 3} \right)\left( {2n + 3} \right)!}}$

Work Step by Step

Write $\dfrac{{t - \sin t}}{t} = \dfrac{1}{t}\left( {t - \sin t} \right)$. From Table 2: $\sin t = \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{t^{2n + 1}}}}{{\left( {2n + 1} \right)!}} = t - \dfrac{{{t^3}}}{{3!}} + \dfrac{{{t^5}}}{{5!}} - \dfrac{{{t^7}}}{{7!}} + \cdot\cdot\cdot$, ${\ \ \ }$ converges for all $t$. Thus, $\dfrac{{t - \sin t}}{t} = \dfrac{1}{t}\left( {t - \sin t} \right) = \dfrac{1}{t}\left( {t - \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{t^{2n + 1}}}}{{\left( {2n + 1} \right)!}}} \right)$, ${\ \ \ }$ converges for all $t$. $\dfrac{{t - \sin t}}{t} = \dfrac{1}{t}\left( {\dfrac{{{t^3}}}{{3!}} - \dfrac{{{t^5}}}{{5!}} + \dfrac{{{t^7}}}{{7!}} + \cdot\cdot\cdot} \right)$ $\dfrac{{t - \sin t}}{t} = \dfrac{{{t^2}}}{{3!}} - \dfrac{{{t^4}}}{{5!}} + \dfrac{{{t^6}}}{{7!}} + \cdot\cdot\cdot = \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{t^{2n + 2}}}}{{\left( {2n + 3} \right)!}}$ Taking the definite integral on the series gives $\mathop \smallint \limits_0^x \dfrac{{t - \sin t}}{t}{\rm{d}}t = \mathop \sum \limits_{n = 0}^\infty \mathop \smallint \limits_0^x \dfrac{{{{\left( { - 1} \right)}^n}{t^{2n + 2}}}}{{\left( {2n + 3} \right)!}}{\rm{d}}t = \mathop \sum \limits_{n = 0}^\infty \left[ {\dfrac{{{{\left( { - 1} \right)}^n}{t^{2n + 3}}}}{{\left( {2n + 3} \right)\left( {2n + 3} \right)!}}} \right]_0^x$ So, $\mathop \smallint \limits_0^x \dfrac{{t - \sin t}}{t}{\rm{d}}t = \mathop \sum \limits_{n = 0}^\infty \dfrac{{{{\left( { - 1} \right)}^n}{x^{2n + 3}}}}{{\left( {2n + 3} \right)\left( {2n + 3} \right)!}}$.
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.