Question

In order to solve the following system of equations by addition, 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 -3 and the bottom equation by 2. B.Multiply the top equation by -2. C.Multiply the top equation by -3. D.Multiply the top equation by 3 and the bottom equation by 4.

Answer 1

c is correct

Explanation:

Answer 2

C should be the answer. Why?
2x - 4y = 5
6x - 3y = 10
Multiply by -3 to the top equation will eliminate the x variable in the system
-3(2x - 4y = 5)
6x - 3y = 10
==> -6x + 12y = -15
6x - 3y = 10
adding top with bottom will eliminate the x
==> -6x + 6x = 0, 12y + (-3y) = 9y, -15 + 10 = -5