Calculus: Early Transcendentals (2nd Edition)

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

Chapter 4 - Applications of the Derivative - 4.8 Newton's Method - 4.8 Exercises - Page 316: 13

Answer

\[\boxed{\begin{array}{*{20}{c}} n&{{x_n}} \\ 0&{1.500000} \\ 1&{1.443890} \\ 2&{1.361976} \\ 3&{1.268175} \\ 4&{1.196179} \\ 5&{1.168571} \\ 6&{1.165592} \\ 7&{1.165561} \\ 8&{1.165561} \\ 9&{1.165561} \\ {10}&{1.165561} \end{array}}\]

Work Step by Step

\[\begin{gathered} {\text{Let }}f\left( x \right) = \tan x - 2x,{\text{ and }}{x_0} = 1.5 \hfill \\ {\text{Using the Newton's Method }}{x_{n + 1}} = {x_n} - \frac{{f\left( {{x_n}} \right)}}{{f'\left( {{x_n}} \right)}} \hfill \\ f'\left( x \right) = {\sec ^2}x - 2 \hfill \\ {\text{Then evaluating }}f\left( {{x_n}} \right){\text{ and }}f'\left( {{x_n}} \right) \hfill \\ {x_{n + 1}} = {x_n} - \frac{{\tan {x_n} - 2{x_n}}}{{{{\sec }^2}{x_n} - 2}} \hfill \\ \hfill \\ {\text{Taking }}{x_0} = 1.5 \hfill \\ {x_0} = 1.5 \hfill \\ {x_{0 + 1}} = {x_1} = 1.5 - \frac{{\tan \left( {1.5} \right) - 2\left( {1.5} \right)}}{{{{\sec }^2}\left( {1.5} \right) - 2}} \approx 1.443890 \hfill \\ {x_{1 + 1}} = {x_2} = 1.443890 - \frac{{\tan \left( {1.443890} \right) - 2\left( {1.443890} \right)}}{{{{\sec }^2}\left( {1.443890} \right) - 2}} \approx 1.361976 \hfill \\ {x_{1 + 2}} = {x_3} = 1.361976 - \frac{{\tan \left( {1.361976} \right) - 2\left( {1.361976} \right)}}{{{{\sec }^2}\left( {1.361976} \right) - 2}} \approx 1.268175 \hfill \\ {x_{1 + 3}} = {x_4} = 1.268175 - \frac{{\tan \left( {1.268175} \right) - 2\left( {1.268175} \right)}}{{{{\sec }^2}\left( {1.268175} \right) - 2}} \approx 1.196179 \hfill \\ {x_{1 + 4}} = {x_5} = 1.196179 - \frac{{\tan \left( {1.196179} \right) - 2\left( {1.196179} \right)}}{{{{\sec }^2}\left( {1.196179} \right) - 2}} \approx 1.168571 \hfill \\ {x_{1 + 5}} = {x_6} = 1.168571 - \frac{{\tan \left( {1.168571} \right) - 2\left( {1.168571} \right)}}{{{{\sec }^2}\left( {1.168571} \right) - 2}} \approx 1.165592 \hfill \\ {x_{1 + 6}} = {x_7} = 1.165592 - \frac{{\tan \left( {1.165592} \right) - 2\left( {1.165592} \right)}}{{{{\sec }^2}\left( {1.165592} \right) - 2}} \approx 1.165561 \hfill \\ {x_{1 + 7}} = {x_8} = 1.165561 - \frac{{\tan \left( {1.165561} \right) - 2\left( {1.165561} \right)}}{{{{\sec }^2}\left( {1.165561} \right) - 2}} \approx 1.165561 \hfill \\ {x_{1 + 8}} = {x_9} = 1.165561 - \frac{{\tan \left( {1.165561} \right) - 2\left( {1.165561} \right)}}{{{{\sec }^2}\left( {1.165561} \right) - 2}} \approx 1.165561 \hfill \\ {x_{1 + 9}} = {x_{10}} = 1.165561 - \frac{{\tan \left( {1.165561} \right) - 2\left( {1.165561} \right)}}{{{{\sec }^2}\left( {1.165561} \right) - 2}} \approx 1.165561 \hfill \\ \hfill \\ {\text{Thus}}{\text{, we obtain}} \hfill \\ \boxed{\begin{array}{*{20}{c}} n&{{x_n}} \\ 0&{1.500000} \\ 1&{1.443890} \\ 2&{1.361976} \\ 3&{1.268175} \\ 4&{1.196179} \\ 5&{1.168571} \\ 6&{1.165592} \\ 7&{1.165561} \\ 8&{1.165561} \\ 9&{1.165561} \\ {10}&{1.165561} \end{array}} \hfill \\ \end{gathered} \]
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