Question

How do you solve the system of equations `x- 3y = - 12` and `- 3x + 4y = 16` by elimination?

Answer 1

x=0, y=4

Explanation:

`x-3y=-12`, if you add 3y to both sides, the left side cancels out, and you get one variable's value: `x=-12+3y`

Now plug that in for x in the second equation.
`-3(-12+3y)+4y=16`

Simplify.
`36-9y+4y=16`
`36-5y=16`
`-5y=-20`
`y=4`

Getting y, we plug that into the equation for x in order to find x.
`x=-12+3(4)=-12+12=0`

Plugging into the first equation to check variables...
`0-3(4)\stackrel{?}{=}-12`
`-12=-12`