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 - Chapter Test - Page 47: 8

Answer

$x=8$ and $x=−4$

Work Step by Step

The given equation is $\Rightarrow |20+2x|=|4x+4|$ Write related linear equations. $\Rightarrow 20+2x=4x+4$ or $20+2x=−(4x+4)$ Solve the first equation. $\Rightarrow 20+2x=4x+4$ Add $-4-2x$ to each side. $\Rightarrow 20+2x-4-2x=4x+4-4-2x$ Simplify. $\Rightarrow 16=2x$ Divide each side by $2$. $\Rightarrow \frac{16}{2}=\frac{2x}{2}$ Simplify. $\Rightarrow 8=x$ Solve the second equation. $\Rightarrow 20+2x=-(4x+4)$ Clear the parentheses. $\Rightarrow 20+2x=-4x-4$ Add $-20+4x$ to each side. $\Rightarrow 20+2x-20+4x=-4x-4-20+4x$ Simplify. $\Rightarrow 6x=-24$ Divide each side by $6$. $\Rightarrow \frac{6x}{6}=\frac{-24}{6}$ Simplify. $\Rightarrow x=-4$ Check $x=8$ $\Rightarrow |20+2(8)|=|4(8)+4|$ $\Rightarrow |20+16|=|32+4|$ $\Rightarrow |36|=|36|$ $\Rightarrow 36=36$ True. Check $x=-4$ $\Rightarrow |20+2(-4)|=|4(-4)+4|$ $\Rightarrow |20-8|=|-16+4|$ $\Rightarrow |12|=|-12|$ $\Rightarrow 12=12$ True. Hence, the solutions are $x=8$ and $x=−4$.
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