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

Sagot :

Let:

[tex]\begin{gathered} 3x+y=-3\text{ (1)} \\ -2x+y=7\text{ (2)} \end{gathered}[/tex]

From (1) solve for y:

[tex]y=-3-3x\text{ (3)}[/tex]

Replace (3) into (2):

[tex]\begin{gathered} -2x+(-3-3x)=7 \\ -2x-3-3x=7 \\ -5x-3=7 \\ -5x=10 \\ x=\frac{10}{-5} \\ x=-2 \end{gathered}[/tex]

Replace x into (3):

[tex]\begin{gathered} y=-3-3(-2) \\ y=-3+6 \\ y=3 \end{gathered}[/tex]