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

1 Answer
May 2, 2018

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