Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 5 - Section 5.7 - Polynomial Equations and Their Applications - Exercise Set - Page 390: 32

Answer

$x=-3$ and $x=3$

Work Step by Step

We solve the given equation: $$\begin{align*} (x+1)^2&=2(x+5)\quad&&\text{Write the given equation.}\\ (x+1)^2-2(x+5)&=0\quad&&\text{Subtract }2(x+5)\text{ from each side.}\\ x^2+2x+1-2x-10&=0\quad&&\text{Perform calculations.}\\ x^2-9&=0\quad&&\text{Write the equation in standard form.}\\ (x+3)(x-3)&=0\quad&&\text{Factor.}\\ x+3=0&\text{ 0r }x-3=0\quad&&\text{Set each factor equal to }0.\\ x=-3&\text{ or }x=3\quad&&\text{Solve the resulting equations.} \end{align*}$$ The equation has two solutions: $x=-3$ and $x=3$. Check the results by substituting them in the original equation: $$\begin{align*} x&=-3\\ (-3+1)^2&\stackrel{?}{=}2(-3+5)\\ (-2)^2&\stackrel{?}{=}2(2)\\ 4&=4\checkmark\\\\ x&=3\\ (3+1)^2&\stackrel{?}{=}2(3+5)\\ (4)^2&\stackrel{?}{=}2(8)\\ 16&=16\checkmark. \end{align*}$$ Both solutions check the equation.
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