SOLUTION: the question says solve the following system of euqations by elimination. x+2z =5 -4x+6y =0 x-2z=9 this is the order that the problem is set up, and i haven't seen anything

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: the question says solve the following system of euqations by elimination. x+2z =5 -4x+6y =0 x-2z=9 this is the order that the problem is set up, and i haven't seen anything      Log On


   

Question 12503: the question says solve the following system of euqations by elimination.
x+2z =5
-4x+6y =0
x-2z=9
this is the order that the problem is set up, and i haven't seen anything like this, so i need a little help on what to do.
thanks matt
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by elimination:
1) x+%2B+2z+=+5
2) -4x+%2B+6y+=+0
3) x+-+2z+=+9
Add equations 1) and 3) to eliminate z.
x+%2B+2z+=+5
x+-+2z+=+9
----------------
2x+=+14
x+=+7 Substitute this value of x into equation 1) and solve for z.
1)
7+%2B+2z+=+5 Subtract 7 from both sides.
2z+=+-2 Divide both sides by 2.
z+=+-1
Substitute x = 7 into equation 2) and solve for y.
-4%287%29+%2B+6y+=+0
-28+%2B+6y+=+0 Add 28 to both sides.
6y+=+28 Divide both sides by 6.
y+=+28%2F6 = 4 2/3
To check the solutions, substitute x = 7, y = 4 2/3, and z = -1 into the original equations. I'll leave for you to do.