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 243: 5

Answer

$(2,-2)$

Work Step by Step

The given system of equations is $\Rightarrow -x+y=-4$ ...... (1) $\Rightarrow 4x-y=10$ ...... (2) Solve for $y$ in equation (1). $\Rightarrow y=-4+x$ ...... (3) Substitute $-4+x$ for $y$ in equation (2). $\Rightarrow 4x-(-4+x)=10$ Clear the parentheses. $\Rightarrow 4x+4-x=10$ Add like terms. $\Rightarrow 3x+4=10$ Subtract $4$ from each side. $\Rightarrow 3x+4-4=10-4$ Simplify. $\Rightarrow 3x=6$ Divide each side by $3$. $\Rightarrow \frac{3x}{3}=\frac{6}{3}$ Simplify. $\Rightarrow x=2$ Substitute $2$ for $x$ in equation (3). $\Rightarrow y=-4+2$ Simplify. $\Rightarrow y=-2$ Check Equation (1) $\Rightarrow -x+y=-4$ $\Rightarrow -2-2=-4$ $\Rightarrow -4=-4$ True. Check Equation (2) $\Rightarrow 4(2)-(-2)=10$ $\Rightarrow 8+2=10$ $\Rightarrow 10=10$ True. Hence, the solution is $(2,-2)$.
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