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 - Chapter Review - Page 282: 5

Answer

The solution is $(2,1)$.

Work Step by Step

The given system of equations is $\Rightarrow x+4y=6$ ...... (1) $\Rightarrow x-y=1$ ...... (2) Add $y$ to each side of equation (2). $\Rightarrow x-y+y=1+y$ $\Rightarrow x=1+y$ ...... (3) Substitute $1+y$ for $x$ in equation (1). $\Rightarrow 1+y+4y=6$ Add like terms. $\Rightarrow 1+5y=6$ Subtract $1$ from each side. $\Rightarrow 1+5y-1=6-1$ Simplify. $\Rightarrow 5y=5$ Divide each side by $5$. $\Rightarrow \frac{5y}{5}=\frac{5}{5}$ Simplify. $\Rightarrow y=1$ Substitute $1$ for $y$ in equation (2). $\Rightarrow x-1=1$ Add $1$ to each side. $\Rightarrow x-1+1=1+1$ Simplify. $\Rightarrow x=2$ Check $(x,y)=(2,1)$ Equation (1) $\Rightarrow x+4y=6$ $\Rightarrow 2+4(1)=6$ $\Rightarrow 2+4=6$ $\Rightarrow 6=6$ True. Equation (2) $\Rightarrow x-y=1$ $\Rightarrow 2-1=1$ $\Rightarrow 1=1$ True. Hence, the solution is $(2,1)$.
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