SOLUTION: Can someone please show me step by step on this please...I did it but I am off 1 number..I appreciate the time. Use matrix form and Gaussian elimination method to solve the line

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Question 368368: Can someone please show me step by step on this please...I did it but I am off 1 number..I appreciate the time.
Use matrix form and Gaussian elimination method to solve the linear system
4x+8y-4z=4
3x+8y+5z= -11
-2x+y+12z= -17
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
4x%2B8y-4z=4
1.x%2B2y-z=1
2.3x%2B8y%2B5z=+-11
3.-2x%2By%2B12z=+-17
Multiply eq. 1 by (-3) and add to eq. 2,
-3x-6y%2B3z%2B3x%2B8y%2B5z=-3-11
2y%2B8z=-14
4.y%2B4z=-7
Multiply eq. 1 by (2) and add to eq. 3,
2x%2B4y-2z-2x%2By%2B12z=2-17
5y%2B10z=-15
5.y%2B2z=-3
Subtract eq. 5 from eq. 4,
y%2B4z-y-2z=-7-%28-3%29
2z=-4
highlight%28+z=-2%29
Then from eq. 4,
y-8=-7
highlight%28+y=1%29
Then from eq. 1,
x%2B2%2B2=1
highlight%28+x=-3%29