Intermediate Algebra: Connecting Concepts through Application

Published by Brooks Cole
ISBN 10: 0-53449-636-9
ISBN 13: 978-0-53449-636-4

Chapter 8 - Radical Functions - 8.4 Solving Radical Equations - 8.4 Exercises - Page 654: 61

Answer

$x= 105.5 $

Work Step by Step

Given\begin{equation} \sqrt[3]{2 x+5}=6. \end{equation}Start by rewriting the radical as a power of fraction and then solve for $x$. \begin{equation} \begin{aligned} \sqrt[3]{2 x+5}&=6\\ \left(2 x+5\right)^{\frac{1}{3}}&= 6\\ \left(\left(2 x+5\right)^{\frac{1}{3}}\right)^3& = \left( 6 \right)^3 \\ 2x+5& =216\\ x&= \frac{216-5}{2}\\ & = 105.5. \end{aligned} \end{equation} Check. \begin{equation} \begin{aligned} \left(2\cdot105.5+5\right)^{\frac{1}{3}}&\stackrel{?}{=}6 \\ 6& =6\quad \checkmark. \end{aligned} \end{equation} The solution is $x= 105.5 $.
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