Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 4 - Exponential and Logarithmic Functions - Section 4.4 Logarithmic Functions - 4.4 Assess Your Understanding - Page 322: 107

Answer

$5\ln(1.4)$

Work Step by Step

Divide $5$ to both sides of the equation to obtain: $5 e^{0.2x} =7$ $e^{0.2x}=\dfrac{7}{5}$ $e^{0.2x}=1.4$ $\because e^y=x \text{ is equivalent to } y=\ln{x}$ $\therefore e^{0.2x} = 1.4 \text{ is equivalent to } 0.2x=\ln{1.4}$ Solve the equation above by multiplying $5$ to both sides of the equation to obtain: \begin{align*} 0.2x&=\ln{1.4}\\ 5(0.2x&)=5(\ln{1.4})\\ x&=5\ln(1.4) \end{align*}
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