Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 6 - Inverse Functions - 6.4* General Logarithmic and Exponential Functions - 6.4* Exercise - Page 464: 53

Answer

$x=0.600967$.

Work Step by Step

Given $y=2^x$ and $y=1+3^{-x}$ From the graph, we can find the intersection point $(0.601,1.517)$ To find the intersection point using (Newton's Method), since \begin{aligned} f(x)& = 2^2-1-3^{-x}\\ f'(x)&= 2^x \ln 2+3^{-x} \ln 3 \end{aligned} Then \begin{aligned} x_{n+1}&=x_n-\frac{f\left(x_n\right) }{ f^{\prime}\left(x_n\right)}\\ &= x_n- \frac{2^{x_n}-1-3^{-x_n}}{2^{x_n} \ln 2+3^{-x_n} \ln 3} \end{aligned} Using $x_0\approx 0.5$ Then \begin{aligned} x_1&= 0.5-\:\frac{2^{0.5}-1-3^{-0.5}}{2^{0.5}\:\ln \:2+3^{-0.5}\:\ln \:3}\approx 0.60104\\ x_2&\approx 0.600967\\ x_3&\approx 0.600967 \end{aligned} So, correct to six decimal places, the root occurs at $x=0.600967$.
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