Question

How do i solve systems of equations by elimination?

Answer 1

Say you had this problem:

-4x - 2y= -12
4x +8y = -24

First you would have to cancel out one part of the equation to get on variable alone. In this case it's easy it would be -4x and 4x. So then you would cancel those out.

Now we have

-2y= -12
8y =-24

so then you just add them all up

6y=-36

Next you just divide both sides by 6
so then you answer for y would be -6.

Next you would choose one of your equations and plug the -6 in.

So it would be

-4x -2 (-6) =-24

So you would times negative 2 by negative 6, which would be positive 12. Since a negative times a negative equales a positive.

-4x + 12= -24

Next you would minus 12 on both sides.

-4x + 12=-24
- 12 = -12

The 12's would cancel out and then you just minus -24 by -12 which you would ended up just plusing them together because a negative plus a negative equales a negative. Or a negative minus a negative number would end up adding them up.

-4x= -36

Next you would get x alone and how you would do that is you would divide -4 in both sides which would cancel them -4 out then it would be divided by -36.

So it would look like this.

-4x= -36
-4 -4

So negative 36 divided by negative 4 is 9.

So your final answer would be

y= -6
x= 9

I hope I explained to you properly how to do systems of equations by elimination.