With whatever method is easiest...substitution or elimination?

## How do you solve 3x+y =-2 and x-y=6?

# 5 Answers

You can also cancel -y and +y just by adding this two equations. so when you add it just left with:

4x=4

x=1

then plug back 1 to one of the equation.

1-y=6

1-6=y

y=-5

I would solve for x with the first equation, then use that to solve for y in the second, then check by inputting values.

3x+y=-2

x-y=6

x=6+y

then...

3(6+y)+y=-2

18+3y+y=-2

18+4y=-2

4y=-20

y=-5

So..

3x+-5=-2

3x=3

x=1

3(1) + -5 = -2 ... yes! :)

This is a system of linear equations that can be solved by elimination and substitution: First we will use elimination to solve for x 3x + y = -2 x- y= 6 Add the 2 equations and the result is: 3x + y = -2 x- y= 6 4x = 4 Divide both sides by 4 (Inverse operation) 4x/4 = 4/4 x= 1 Substitute 1 for x in the 1st equation 3 (1) + y = -2 3 + y = -2 Subtract 3 from both sides (Inverse operation) 3-3 +y = -2 - 3 y = -2 + -3 y = -5 Substitute the solution for x and y into both equations to verify. 3(1) + -5 = -2 3 + -5 = -2 -2 = -2 1-(-5) = 6 1+5 = 6 6=6

SO the first answer is Substitution and the Second answer offered is using Elimination. I would say in this case the Elimination is easier, but both are quite simple for this problem.

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