Question

How do you solve the system of equations `y= - 3x - 6` and `- 4x + y = - 20`?

Answer 1

`x=2,y=-12`

Explanation:

Apply substitution, since one of the equations basically gives a formula for one variable.

`y=-3x-6` and `-4x+y=-20`
`\therefore-4x+(-3x-6)=-20`

Solve this modified equation for variable `x`:
`-4x-3x-6=-20`
`-7x-6=-20`
`-7x=-14`
`x=2`

Replace said variable in the equation for `y`:
`y=-3(2)-6`
`y=-6-6`
`y=-12`