Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 3 - Linear Systems - 3-6 Solving Systems Using Matrices - Practice and Problem-Solving Exercises - Page 181: 54

Answer

The solutions are $y = \frac{15}{2}$ and $y = -\frac{9}{2}$.

Work Step by Step

Use the rule $\quad |a|=b \implies a=b \text{ or } a=-b \quad$ to obtain: $2y - 3 = 12$ or $2y - 3 = -12$ Now, we solve each equation. For the first equation we have: $2y - 3 = 12$ $2y = 3 + 12$ $2y = 15$ Divide both sides of the equation by $2$ to solve for $y$: $y = \frac{15}{2}$ For the second equation: $2y - 3 = -12$ $2y = 3 - 12$ $2y = -9$ Divide both sides of the equation by $2$ to solve for $y$: $y = -\frac{9}{2}$ Checking: For $y=-\frac{9}{2}$: \begin{align*} \left|2\left(-\frac{9}{2}\right)-3\right|&=12\\ \left|-9-3\right|&=12\\ \left|-12\right|&=12\\ 12&=12\end{align*} For $y=\frac{15}{2}$: \begin{align*} \left|2\left(\frac{15}{2}\right)-3\right|&=12\\ \left|15-3\right|&=12\\ \left|12\right|&=12\\ 12&=12\end{align*} Therefore, the solutions are $y = \frac{15}{2}$ and $y = -\frac{9}{2}$.
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