Question

How do you solve this system of equations using the addition method: `4x - y = - 4;5x + 2y = - 18`?

Answer 1

`x=-2, y=-4`

Explanation:

Right now, you have:
`4x-y=-4`
`5x+2y=-18`

To make this easier, you must get rid of one variable, in this case I will remove `y`, to do this you must make the y-values in both equations the same.

To do this, I will multiply the whole of `4x-y=-4` by 2 to give `8x-2y=-8`

We now have:
`8x-2y=-8`
`5z+2y=-18`

All we need to do now is `(8x-2y+5x+2y)=(-18-8)-=13x=-26`.

Divide both sides by 13 to find `x`:
`13x=-26`
`(13x)/13=-26/13`
`x=-2`

Now put your value for `x` into either equation:
`4(-2)-y=-4`
`-8-y=-4`
`y=-8+4`
`y=-4`

`x=-2; y=-4`