How do solve the following linear system?: -4x + 4 = -y, 3x + 6y + 13 = 0 ?

1 Answer
EZ as pi
May 31, 2017

x = 11/27 and y = -2 17/27

Explanation:

It might be better to work on the first equation a little and multiply by -1 so the y term is positive. Then we have an equation which is suitable for the substitution method:

-4x +4 = -y" "rarr (xx-1)" "rarrcolor(blue)(4x-4 = y)

Substitute color(blue)((4x-4)) for y in the other equation:

3x+6color(blue)( y) +13=0

3x+6color(blue)((4x-4)) +13=0" "larr only x terms

3x+24x = -13+24

27x = 11

x = 11/27

Now use x=11/27 to find a value for y

y =4x-4 = 4(11/27)-4

y= -2 10/27

Checking into the second equation confirms these results:
0=0

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