Question

How do you solve 5x - 3y = -20 and -3x + 6y = 12?

Answer 1

The solution is
`color(blue)(x=-4, y=0`

Explanation:

`5x - 3y = -20`, multiplying this equation by `2`
`10x - color(blue)(6y) = -40`......equation `1`

`-3x + color(blue)(6y) = 12`......equation `2`

Solving the equation by elimination .

Adding equations `1` and `2` results in elimination of `color(blue)(6y`

`10x - cancelcolor(blue)(6y) = -40`
`-3x + cancelcolor(blue)(6y) = 12`

`7x= -28`

`x= -28/7`

`color(blue)(x=-4`

Substituting `x` in equation `1` to find `y`
`5x - 3y = -20`

`5x +20 = 3y`

`5*(-4) +20 = 3y`

`-20 +20 = 3y`

`3y=0`

`color(blue)(y=0`