Question

If you use the elimination method to solve the system of equations, 3x - 4y = 9 and 2x 3y = 7, which of the following would be the best method? method i: multiply both sides of the first equation by 2, and multiply both sides of the second equation by 3. then add the two equations. method ii: multiply both sides of the first equation by 3, and multiply both sides of the second equation by 4. then add the two equations.

Answer 1

Method ii
When adding the y terms after multiplying each equation, they cancel out and become zero leaving just an x term. This makes it solvable

If you chose method i
After adding the equations, no terms cancel and we still have an x and a y term which isn't good.

So method ii is correct.