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: 6

Answer

$(6,17)$

Work Step by Step

The given system of equations is $\Rightarrow 2x-y=-5$ ...... (1) $\Rightarrow 3x-y=1$ ...... (2) Solve for $y$ in equation (2). $\Rightarrow 3x-y=1$ $\Rightarrow 3x=1+y$ $\Rightarrow 3x-1=y$ ...... (3) Substitute $3x-1$ for $y$ in equation (1). $\Rightarrow 2x-(3x-1)=-5$ Clear the parentheses. $\Rightarrow 2x-3x+1=-5$ Add like terms. $\Rightarrow -x+1=-5$ Add $x+5$ to each side. $\Rightarrow -x+1+x+5=-5+x+5$ Simplify. $\Rightarrow 6=x$ Substitute $6$ for $x$ in equation (3). $\Rightarrow y=3(6)-1$ Simplify. $\Rightarrow y=18-1$ $\Rightarrow y=17$ Check Equation (1) $\Rightarrow 2x-y=-5$ $\Rightarrow 2(6)-(17)=-5$ $\Rightarrow 12-17=-5$ $\Rightarrow -5=-5$ True. Check Equation (2) $\Rightarrow 3x-y=1$ $\Rightarrow 3(6)-(17)=1$ $\Rightarrow 18-17=1$ $\Rightarrow 1=1$ True. Hence, the solution is $(6,17)$.
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