Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 5 - Logarithmic, Exponential, and Other Transcendental Functions - 5.2 Exercises - Page 335: 85

Answer

$x=2$

Work Step by Step

LHS = $3\displaystyle \int_{1}^{x}\frac{1}{t}dt=$ Log Rule = $3\ln|t|_{1}^{x}$ $LHS= 3\ln x-3\ln 1=3\ln x$ $RHS$ = log rule = $\ln|t|_{1/4}^{x}$ = $\displaystyle \ln x-\ln\frac{1}{4}$ $=\ln x-\ln 4^{-1}=\ln x+\ln 4$ $LHS=RHS$ is now a logarithmic equation... $3\ln x=\ln x+\ln 4\qquad/-\ln x$ $ 2\ln x=\ln 2^{2}\qquad$ /RHS ... log of a power... $ 2\ln x=2\ln 2\qquad$ .../$\div 2$ $\ln x=\ln 2\qquad $/... apply $e^{(..)}$ to both sides $x=2$
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