Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 9 - Section 9.7 - Common Logarithms, Natural Logarithms, and Change of Base - Exercise Set - Page 585: 40

Answer

$x=\frac{e^{3.4}-5}{2}\approx12.4821$

Work Step by Step

We are given the equation $\ln(2x+5)=3.4$. To solve for x, remember that the base of a natural logarithm is understood to be $e$. Therefore, $\ln(2x+5)=log_{e}(2x+5)=3.4$. If $b\gt0$ and $b\ne1$, then $y=log_{b}x$ means $x=b^{y}$ for every $x\gt0$ and every real number $y$. Therefore, $2x+5=e^{3.4}$. Subtract 5 from both sides. $2x=e^{3.4}-5$ Divide both sides by 2. $x=\frac{e^{3.4}-5}{2}\approx12.4821$
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