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Use the substitution method to solve the system of equations. choose the correct ordered pair.

3x- y=3
Y=2x +2

A. (2,6)
B. (5,12)
C. (4,10)
D.(3,8)

User Bobbypage
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2 Answers

2 votes

It’s 5 & 12. Just substitute them in and boom!

User BossRoss
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5 votes

Answer: Choice B. (5, 12)

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Step-by-step explanation:

Start with the first equation. We'll plug in y = 2x+2

3x - y = 3

3x - ( y ) = 3

3x - ( 2x+2 ) = 3 ..... replace y with 2x+2

3x - 2x - 2 = 3 ..... distribute the negative through to all terms inside

x-2 = 3 ............ combine like terms

x-2+2 = 3+2 .... add 2 to both sides

x = 5

Use this x value to find the value of y. The easiest equation to use is the one in which y is already isolated for us

y = 2x+2

y = 2*5+2 ..... replace x with 5

y = 10+2

y = 12

Though we can use the other equation as well

3x-y = 3

3*5-y = 3 .... replace x with 5

15 - y = 3

15-y-15 = 3-15 ..... subtract 15 from both sides

-y = -12

y = 12 ..... multiply both sides by -1, or change the signs of both sides

We get the same result for y.

The solution is (x,y) = (5,12) meaning that the graphs of the two original equations cross at this point.

User Alanaktion
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