Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 1 - Solving Linear Equations - 1.4 - Solving Absolute Value Equations - Monitoring Progress - Page 29: 5

Answer

$x=-\frac{3}{2}$ and $x=-\frac{11}{2}$

Work Step by Step

The given equation is $\Rightarrow 4|2x+7|=16$ Divide each side by $4$. $\Rightarrow \frac{4|2x+7|}{4}=\frac{16}{4}$ Simplify. $\Rightarrow |2x+7|=4$ Write related linear equations. $\Rightarrow 2x+7=4$ or $2x+7=−4$ Subtract $7$ from each side. $\Rightarrow 2x+7-7=4-7$ or $2x+7-7=−4-7$ Simplify. $\Rightarrow 2x=-3$ or $2x=−11$ Divide each side by $2$. $\Rightarrow \frac{2x}{2}=-\frac{3}{2}$ or $\frac{2x}{2}=−\frac{11}{2}$ Simplify. $\Rightarrow x=-\frac{3}{2}$ or $x=−\frac{11}{2}$ Check $x=-\frac{3}{2}$ $\Rightarrow 4|2(-\frac{3}{2})+7|=16$ $\Rightarrow 4|-3+7|=16$ $\Rightarrow 4|4|=16$ $\Rightarrow 4(4)=16$ $\Rightarrow 16=16$ True. Check $x=-\frac{11}{2}$ $\Rightarrow 4|2(-\frac{11}{2})+7|=16$ $\Rightarrow 4|-11+7|=16$ $\Rightarrow 4|-4|=16$ $\Rightarrow 4(4)=16$ $\Rightarrow 16=16$ True. Hence, the solutions are $x=-\frac{3}{2}$ and $x=-\frac{11}{2}$.
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