Question

How do you solve the system of equations `y= 3x + 12` and `2x - 2y = - 4`?

Answer 1

Substitution.

Explanation:

`y=3x+12 " " " "(1)`

`2x-2y =-4`

`-2y=-4-2x`

So

`y=(-4-2x)/-2`

`y= 2+x" " " "(2)`

Sub `(2)` into `(1)`

`3x+ 12= 2 +x`

`2x=-10`

`x=-5`

Sub `x=-5` into `(1)` (I would normally sub it into a given equation as I may have done a mistake in my new equation)

`y= 3(-5)+12`

`y=-3`

Therefore,

`y= -3 and x= -5`