Question

What is a possible first step in eliminating a variable in the following system of equations?

x + 7y = –15
2x + 7y = –9

Answer 1

MY answer choices

Multiply the first equation by –1.

Multiply the second equation by –1

Multiply the first equation by –2.

All of the above

Answer 2

Try doing each one... first, do one of your options, like multiply the first equation by -1. Now add it to the 2nd equation and see if a variable disappears. So for the first case, you have \[(x+7y=-15) *(-1)\] which gives you \[-x-7y=15\]
If you add that to the 2nd equation, you'll eliminate the 7y.

Try for the other 2.

Answer 3

all of the above :)