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.

Answer 1

D. Multiply the 2nd question by -3

Answer 2

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.