SOLUTION: i dont understand how to do this: 3x+2y=-6 x=y+3

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: i dont understand how to do this: 3x+2y=-6 x=y+3      Log On


   



Question 267425: i dont understand how to do this:
3x+2y=-6
x=y+3

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
i don't understand how to do this:
3x + 2y =-6
x = y+3
:
Since x = (y+3), why not substitute (y+3) for x in the 1st equation so you have:
3(y+3) + 2y = -6
:
Multiply what's inside the brackets by 3
3y + 9 + 2y = -6
;
Subtract 9 from both sides, add the y's
3y + 2y = -6 - 9
5y = -15
:
Divide both sides by 5
y = %28-15%29%2F5
y = -3
:
Remember that x = y + 3; substitute -3 for y
x = (-3) + 3
x = 0
:
:
Check the solution by substituting for x and y in the 1st equation
3x + 2y =-6
3(0) + 2(-3) = -6
-6 = -6; confirms the solutions