SOLUTION: I have a 3 variable equation similar to the one answered earlier but I still can't grasp it because variables are missing. Can someone solve it to get me on track? x + 2y + z =

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: I have a 3 variable equation similar to the one answered earlier but I still can't grasp it because variables are missing. Can someone solve it to get me on track? x + 2y + z =      Log On


   



Question 1726: I have a 3 variable equation similar to the one answered earlier but I still can't grasp it because variables are missing. Can someone solve it to get me on track?
x + 2y + z =6
x + y =4
3x + y + z =8

Answer by Ne0(6) About Me  (Show Source):
You can put this solution on YOUR website!
There are many different methods involved that you can do to solve this system of equations. By far the easiest way is to enter the value into a matrix and then getting the matrix into reduced-row echelon form to solve the x,y,and z value. You can also do elimination or substitution. Lets look at the second equation first and notice that there are only two variables. We can subtract the y to get x by itself like so: x=4-y.
Now we look at the 1st equation and the last equation. Since the second equation does not have a z variable in it we want to do an elimination. We can multiply the last equation by -1 to get: -3x-y-z=-8.
We can then take both equations then add them together like so:
x+2y+z=6
-3x-y-z=-8
-2x+y=-2
With our new equation of -2x+y=-2 we can substitute the x=4-y into that to get: -2%284-y%29%2By=-2 which we can simplify to get y by itself which is y=2.
Now that we have our y value we can back substitute into x=4-y to get our x value of x=2.
We finally substitute the x and y value into any of the equations to get the z value which is z=0.
Our values are x=2, y=2, and z=0 or (2,2,0).