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 - 5.3 - Solving Systems of Linear Equations by Elimination - Exercises - Page 251: 5

Answer

The solution is $(4,5)$.

Work Step by Step

The given system of equations is $5x+6y=50$ ...... (1) $x-6y=-26$ ...... (2) Add equation (1) and (2). $\Rightarrow 5x+6y+x-6y=50-26$ Add like terms. $\Rightarrow 6x=24$ Divide each side by $6$. $\Rightarrow \frac{6x}{6}=\frac{24}{6}$ Simplify. $\Rightarrow x=4$ Substitute $4$ for $x$ equation (1). $\Rightarrow 5(4)+6y=50$ Simplify. $\Rightarrow 20+6y=50$ Subtract $20$ from each side. $\Rightarrow 20+6y-20=50-20$ Simplify. $\Rightarrow 6y=30$ Divide each side by $6$. $\Rightarrow \frac{6y}{6}=\frac{30}{6}$ Simplify. $\Rightarrow y=5$ Check $(x,y)=(4,5)$ Equation (1): $\Rightarrow 5x+6y=50$ $\Rightarrow 5(4)+6(5)=50$ $\Rightarrow 20+30=50$ $\Rightarrow 50=50$ True. Equation (2): $\Rightarrow x-6y=-26$ $\Rightarrow 4-6(5)=-26$ $\Rightarrow 4-30=-26$ $\Rightarrow -26=-26$ True. Hence, the solution is $(4,5)$.
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