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Y = 2x − 7
−y = 4x + 1

User Ginge
by
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1 Answer

2 votes

Answer:

x=1

y=−5

Explanation:

Consider the first equation. Subtract 2x from both sides.

y−2x=−7

Consider the second equation. Subtract 4x from both sides.

−y−4x=1

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

y−2x=−7,−y−4x=1

Choose one of the equations and solve it for y by isolating y on the left hand side of the equal sign.

y−2x=−7

Add 2x to both sides of the equation.

y=2x−7

Substitute 2x−7 for y in the other equation, −y−4x=1.

−(2x−7)−4x=1

Multiply −1 times 2x−7.

−2x+7−4x=1

Add −2x to −4x.

−6x+7=1

Subtract 7 from both sides of the equation.

−6x=−6

Divide both sides by −6.

x=1

Substitute 1 for x in y=2x−7. Because the resulting equation contains only one variable, you can solve for y directly.

y=2−7

Add −7 to 2.

y=−5

The system is now solved.

y=−5,x=1

User Michaella
by
8.5k points