College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 6 - Section 6.6 - Logarithmic and Exponential Equations - 6.6 Assess Your Understanding - Page 466: 89

Answer

$x=0$

Work Step by Step

Multiply $e^x$ to both sides to obtain: \begin{align*} e^x\left(\frac{e^x+e^{-x}}{2}\right)&=1(e^x)\\\\ \frac{e^x\cdot e^x+e^x\cdot e^{-x}}{2}&=e^x\\\\ \frac{e^{2x}+e^{x+(-x)}}{2}&=e^x\\\\ \frac{e^{2x}+e^0}{2}&=e^x\\\\ \frac{e^{2x}+1}{2}&=e^x\\\\ \end{align*} Multiply $2$ to both sides to obtain: \begin{align*} 2\left(\frac{e^{2x}+1}{2}\right)&=e^x(2)\\\\ e^{2x}+1&=2e^x\\\\ e^{2x}+1-2e^x&=0\\\\ e^{2x}-2e^x+1&=0\\\\ \end{align*} Factor the trinomial to obtain: \begin{align*} (e^x-1)(e^x-1)&=0\\ (e^x-1)^2&=0\end{align*} Use the Zero-Product Prperty by equating each unique factor to zero, then solve the equation to obtain: \begin{align*} e^x-1&=0\\ e^x&=1\\ \ln{(e^x)}&=\ln1\\ x&=0 \end{align*} Therefore, the solution is $x=0$.
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