Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 9 - Power Series - 9.3 Taylor Series - 9.3 Exercises - Page 695: 26

Answer

\[\begin{align} & \left. a \right)2+2\left( x-\ln 2 \right)+{{\left( x-\ln 2 \right)}^{2}}+\frac{1}{3}{{\left( x-\ln 2 \right)}^{3}} \\ & \left. b \right)\sum\limits_{k=0}^{\infty }{\frac{2}{k!}}{{\left( x-\ln 2 \right)}^{k}} \\ \end{align}\]

Work Step by Step

\[\begin{align} & f\left( x \right)={{e}^{x}},\text{ }a=\ln 2 \\ & \text{Using the definition of Taylor series for a function}\left( page\,685 \right) \\ & \sum\limits_{k=0}^{\infty }{\frac{{{f}^{\left( k \right)}}\left( a \right)}{k!}{{\left( x-a \right)}^{k}}}\text{ }\left( \mathbf{1} \right) \\ & =f\left( a \right)+f'\left( a \right)\left( x-a \right)+\frac{f''\left( a \right)}{2!}{{\left( x-a \right)}^{2}}+\cdots \\ & \text{Calculate some derivatives and their value at }x=\ln2 \\ & f\left( x \right)={{e}^{x}}\to f\left( \ln 2 \right)={{e}^{\ln 2}}=2 \\ & f'\left( x \right)={{e}^{x}}\to f\left( \ln 2 \right)={{e}^{\ln 2}}=2 \\ & f''\left( x \right)={{e}^{x}}\to f\left( \ln 2 \right)={{e}^{\ln 2}}=2 \\ & f'''\left( x \right)={{e}^{x}}\to f\left( \ln 2 \right)={{e}^{\ln 2}}=2 \\ & \\ & \left. a \right)\text{ Substituting the previous result into the formula }\left( \mathbf{1} \right). \\ & \left( \text{Using the nonzero coefficients} \right) \\ & =\frac{2}{0!}{{\left( x-\ln 2 \right)}^{0}}+\frac{2}{1!}{{\left( x-\ln 2 \right)}^{1}}+\frac{2}{2!}{{\left( x-\ln 2 \right)}^{2}}+\frac{2}{3!}{{\left( x-\ln 2 \right)}^{3}}\left( \mathbf{2} \right) \\ & \\ & \text{Simplifying} \\ & =2+2\left( x-\ln 2 \right)+{{\left( x-\ln 2 \right)}^{2}}+\frac{1}{3}{{\left( x-\ln 2 \right)}^{3}} \\ & \\ & \left. b \right)\text{ Taking the result }\left( \mathbf{2} \right) \\ & =\frac{2}{0!}{{\left( x-\ln 2 \right)}^{0}}+\frac{2}{1!}{{\left( x-\ln 2 \right)}^{1}}+\frac{2}{2!}{{\left( x-\ln 2 \right)}^{2}}+\frac{2}{3!}{{\left( x-\ln 2 \right)}^{3}} \\ & \text{Using summation notation}\text{, we obtain} \\ & =\sum\limits_{k=0}^{\infty }{\frac{2}{k!}}{{\left( x-\ln 2 \right)}^{k}} \\ \end{align}\]
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.