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 - 5.1-5.4 - Quiz - Page 260: 9

Answer

The solution is $(2,3)$.

Work Step by Step

The given system of equations is $2x-3y=-5$ ...... (1) $5x+2y=16$ ...... (2) Multiply equation (1) by $2$. $2(2x-3y)=2(-5)$ Use distributive property. $4x-6y=-10$ ...... (3) Multiply equation (2) by $3$. $3(5x+2y)=3(16)$ Use distributive property. $15x+6y=48$ ...... (4) Add equation (3) and (4). $\Rightarrow 4x-6y+15x+6y=-10+48$ Add like terms. $\Rightarrow 19x=38$ Divide each side by $19$. $\Rightarrow \frac{19x}{19}=\frac{38}{19}$ Simplify. $\Rightarrow x=2$ Substitute $2$ for $x$ in equation (2). $\Rightarrow 5(2)+2y=16$ Simplify. $\Rightarrow 10+2y=16$ Subtract $10$ from each side. $\Rightarrow 10+2y-10=16-10$ Simplify. $\Rightarrow 2y=6$ Divide each side by $2$. $\Rightarrow \frac{2y}{2}=\frac{6}{2}$ Simplify. $\Rightarrow y=3$ Check $(x,y)=(2,3)$ Equation (1): $\Rightarrow 2x-3y=-5$ $\Rightarrow 2(2)-3(3)=-5$ $\Rightarrow 4-9=-5$ $\Rightarrow -5=-5$ True. Equation (2): $\Rightarrow 5x+2y=16$ $\Rightarrow 5(2)+2(3)=16$ $\Rightarrow 10+6=16$ $\Rightarrow 16=16$ True. Hence, the solution is $(2,3)$.
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