Question

{3x+y = -3{2x+y= 7 Solving systems of equations by substitution

Answer 1

Let:

`\begin{gathered} 3x+y=-3\text{ (1)} \\ -2x+y=7\text{ (2)} \end{gathered}`

From (1) solve for y:

`y=-3-3x\text{ (3)}`

Replace (3) into (2):

`\begin{gathered} -2x+(-3-3x)=7 \\ -2x-3-3x=7 \\ -5x-3=7 \\ -5x=10 \\ x=(10)/(-5) \\ x=-2 \end{gathered}`

Replace x into (3):

`\begin{gathered} y=-3-3(-2) \\ y=-3+6 \\ y=3 \end{gathered}`