How do you solve the following system?: x + 2y = 6 , 3x + 4 = -4y

1 Answer
Apr 7, 2018

x = -16, y = 11

Explanation:

I’m going to be using elimination:

First isolate 4 by subtracting 3x from both sides:

3x + 4 = -4y
-3x -4y =4

Now I’m going to line the two equations up to see which variable I can cancel out first

x+2y=6
-3x-4y=4

I choose y because it seems to be the cleanest out of the two. Now multiply the first equation by 2 in order to cancel out y and then solve for x

2(x+2y=6) = 2x+4y=12

2x+4y=12
+
-3x-4y=4
———————
-x=16
x=-16

Time to solve for y by plugging in -16 for x in either equation. It’s best to choose the equation that seems more efficient

(-16) +2y=6
+16

{2y}/2 =22/2

y=11