Question

How do you solve the following system: `y = 3x – 12, 2x-3y=-13`?

Answer 1

`color(white)(xx)x=7` and `y=9`

Explanation:

`color(white)(xx)y=3x-12, 2x-3y=-13`

`color(white)(xx)2x-3y=-13<=>y=(2x+13)/3`

`=>color(red)(3x-12)=(2x+13)/3`
`=>color(red)(3xx)(3x-12)=color(red)(3xx)(2x+13)/3`
`=>9x-36color(red)(-2x+36)=2x+13color(red)(-2x+36)`
`=>color(red)(1/7xx)7x=color(red)(1/7xx)49`
`=>x=7`

`color(white)(xx)y=3x-12`
`color(white)(xxx)=3xxcolor(red)7-12`
`color(white)(xxx)=9`