In order to solve the following system of equation by addtion, which of the following could you do before adding the equations so that one variable will be eliminated when you add them?
2x-4y=5
6x-3y=10
A. Multiply the top equation by -2
B. Multiply the top equation by 3 and the bottom equation by 4
C. Multiply the top equation by -3 and the bottom equation by 2
D. Multiply the top equation by -3

Question

In order to solve the following system of equation by addtion, which of the following could you do before adding the equations so that one variable will be eliminated when you add them?
2x-4y=5
6x-3y=10
A. Multiply the top equation by -2
B. Multiply the top equation by 3 and the bottom equation by 4
C. Multiply the top equation by -3 and the bottom equation by 2
D. Multiply the top equation by -3

robtobey2 · Answer

D. Looks the most efficient.  The x terms will then subtract out.

lilah · Answer

Thanks @robtobey2

ciarán95 · Answer

Yes, as @robtobey2 said,  D is the only one of the four options which seems to work. All the other options won't lead you to be able to cancel the x's or y's straight away.

lilah · Answer

Thanks for explaining thanks to both of u :)

robtobey2 · Answer

Your welcome.

ciarán95 · Answer

No worries :D