Question

For the following system, if you isolated x in the second equation to use the Substitution Method, what expression would you substitute into the first equation?
2x + y = 8
-x - 3y = -12

A) 3y + 12
B) -3y + 12
C) 3y - 12
D) -3y - 12

Answer 1

-x - 3y = -12

add 3y to both sides:
-x = 3y - 12

divide both sides by -1:
x = -3y + 12

Answer 2

so the answer is b

Answer 3

does that make sense?

Answer 4

Umm..kind of. This always confuses me lol how would I add 3y to both sides if on the other side it's just -x..? @AriPotta

Answer 5

adding 3y to the right side cancels the -3y out. so you're just left with -x

Answer 6

left side*

Answer 7

Ooohhh okay okay makes sense!

Answer 8

do you want me to draw it for you? might make more sense?

Answer 9

Yes please :)