Question

If you wanted to eliminate the y variable by adding the two equations in the following system, what could be your first step?

2x − 4y = 6
3x − y = 12

Add the two equations together

Multiply the first equation by −4

Multiply the second equation by −4

Multiply the second equation by 4

Answer 1

If you want to eliminate the y's when you add, then you would have to multiply the second equation by -4. That would give you a -4y in the top equation and a +4y in the bottom equation, which would add up to 0y when you add the two equations.