Calculus (3rd Edition)

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

Chapter 4 - Applications of the Derivative - 4.7 Newton's Method - Exercises - Page 219: 2

Answer

\begin{align*} x_1 & = 2.66666 \\ x_2& = 2.6190\\ x_3& =2.6180 \end{align*}

Work Step by Step

Given $$ f(x)=x^{2}-3 x+1, \quad x_{0}=3$$ Since $$ x_{n+1}=x_{n}-\frac{f\left(x_{n}\right)}{f^{\prime}\left(x_{n}\right)}$$ Then \begin{align*} x_{n+1}&= x_n -\frac{x_n^{2}-3 x_n+1}{2x_n-3}\\ &= \frac{x_n^{2}-1}{2x_n-3} \end{align*} Hence \begin{align*} x_1 &= \frac{x_0^{2}-1}{2x_0-3}= \frac{(3)^{2}-1}{2(3)-3}= 2.66666 \\ x_2&=\frac{x_1^{2}-1}{2x_1-3}= \frac{(2.66666)^{2}-1}{2(2.66666)-3}= 2.6190\\ x_3&= \frac{x_1^{2}-1}{2x_1-3}= \frac{(2.6190)^{2}-1}{2(2.6190)-3}=2.6180 \end{align*}
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