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 - Exercises - Page 33: 42

Answer

The solutions are $a=\frac{5}{2}$ and $a=\frac{1}{2}$.

Work Step by Step

The given equation is $\Rightarrow |6a-5|=4a$ Write the two related linear equations. $6a-5=4a$ ...... (1) $6a-5=-4a$ ...... (2) Solve equation (1). $\Rightarrow 6a-5=4a$ Add $5-4a$ to each side. $\Rightarrow 6a-5+5-4a=4a+5-4a$ Simplify. $\Rightarrow 2a=5$ Divide each side by $2$. $\Rightarrow \frac{2a}{2}=\frac{5}{2}$ Simplify. $\Rightarrow a=\frac{5}{2}$ Check : $a=\frac{5}{2}$ $\Rightarrow |6a-5|=4a$ $\Rightarrow |6(\frac{5}{2})-5|=4(\frac{5}{2})$ $\Rightarrow |15-5|=10$ $\Rightarrow |10|=10$ $\Rightarrow 10=10$ True. Solve equation (2). $\Rightarrow 6a-5=-4a$ Add $5+4a$ to each side. $\Rightarrow 6a-5+5+4a=-4a+5+4a$ Simplify. $\Rightarrow 10a=5$ Divide each side by $10$. $\Rightarrow \frac{10a}{10}=\frac{5}{10}$ Simplify. $\Rightarrow a=\frac{1}{2}$ Check : $a=\frac{1}{2}$ $\Rightarrow |6a-5|=4a$ $\Rightarrow |6(\frac{1}{2})-5|=4(\frac{1}{2})$ $\Rightarrow |3-5|=2$ $\Rightarrow |-2|=2$ $\Rightarrow 2=2$ True. Hence, the solutions are $a=\frac{5}{2}$ and $a=\frac{1}{2}$.
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