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 5 - Solving Systems of Linear Equations - 5.2 - Solving Systems of Linear Equations by Substitution - Monitoring Progress - Page 242: 2

Answer

$(\frac{1}{2},-\frac{3}{4})$

Work Step by Step

The given system of equations is $\Rightarrow 3x+2y=0$ ...... (1) $\Rightarrow y=\frac{1}{2}x-1$ ...... (2) Substitute $\frac{1}{2}x-1$ for $y$ in equation (1). $\Rightarrow 3x+2(\frac{1}{2}x-1)=0$ Use distributive property. $\Rightarrow 3x+x-2=0$ Add like terms. $\Rightarrow 4x-2=0$ Add $2$ to each side. $\Rightarrow 4x-2+2=0+2$ Simplify. $\Rightarrow 4x=2$ Divide each side by $4$. $\Rightarrow \frac{4x}{4}=\frac{2}{4}$ Simplify. $\Rightarrow x=\frac{1}{2}$ Substitute $\frac{1}{2}$ for $x$ in equation (2). $\Rightarrow y=\frac{1}{2}(\frac{1}{2})-1$ Simplify. $\Rightarrow y=\frac{1}{4}-1$ Add fraction. $\Rightarrow y=\frac{1-4}{4}$ Simplify. $\Rightarrow y=-\frac{3}{4}$ Check Equation (1) $\Rightarrow 3x+2y=0$ $\Rightarrow 3(\frac{1}{2})+2(-\frac{3}{4})=0$ $\Rightarrow \frac{3}{2}-\frac{3}{2}=0$ $\Rightarrow 0=0$ True. Check Equation (2) $\Rightarrow y=\frac{1}{2}x-1$ $\Rightarrow -\frac{3}{4}=\frac{1}{2}(\frac{1}{2})-1$ $\Rightarrow -\frac{3}{4}=\frac{1}{4}-1$ $\Rightarrow -\frac{3}{4}=\frac{1-4}{4}$ $\Rightarrow -\frac{3}{4}=-\frac{3}{4}$ True. Hence, the solution is $(\frac{1}{2},-\frac{3}{4})$.
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