Question

X-12y=-7 3x-6y=-21 how do I solve ?

Answer 1

Use linear combination to eliminate one term in the equation.

Explanation:

The goal is to completely remove one variable from both sets of equations. The best way to do this is to combine both equations and manipulate them beforehand for elimination.

`x-12y=-7`
`(3x-6y=-21)xx2`

Multiply this equation by `2` so you have `12y` in both. Then, add/ subtract the equations from each other (choose the operation that will eliminate a variable, so in this case it is subtraction)

`x-12y=-7`
`6x-12y=-42" " " "` Subtract them straight down.

`-5x= 35`

`x= (-35)/5`

`x = -7`

Plug `x` into either equation to solve for `y`.

`-7 - 12y = -7`

`-12y = 0`

`y = 0`