Which of the following would be the best first step to solve the system of equations?
2x – 9y = 6
4x – 3y = –7

A. Multiply the first equation by 2.
B. Multiply the second equation by 2.
C. Multiply the first equation by –3.
D. Multiply the second equation by –3.

Question

Which of the following would be the best first step to solve the system of equations?     
2x – 9y = 6
4x – 3y = –7

A. Multiply the first equation by 2.
B. Multiply the second equation by 2.
C. Multiply the first equation by –3.     
D. Multiply the second equation by –3.

anonymous · Answer

D. Multiply the 2nd question by -3

anonymous · Answer

You want to get the multipliers for either the x or y values to be the same, so you can subtract them, isolating the problem to the other variable.

ax + by = c
ex + fy = g

multiply first equation by e/a and then subtract second from first to get an equation in y only.