How do you solve the system of equations x- 4y = 12 and 5x + 4y = - 12?

1 Answer
Dec 3, 2016

The solution is (0,-3)

Explanation:

color(white)ax-4y=color(white)(aa)12
5x+4y=-12

Add the equations together vertically.

color(white)ax-4y=color(white)(aa)12
ul(5x+4y=-12)
6x+0color(white)(a)=color(white)(aa)0

6x=0

(6x)/6=0/6color(white)(aaa)Divide both sides by 6

x=0

Substitute color(red)x=color(red)0 into the first equation.

color(red)0-4y=12

-4y=12

(-4y)/-4=12/-4color(white)(aaa)Divide both sides by -4

y=-3

The solution is (0,-3)