SOLUTION: Solve the system by elimination. -x-5y-5z=2 4x-5y+4z=19 x+5y-z=-20

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Question 1023813: Solve the system by elimination.
-x-5y-5z=2
4x-5y+4z=19
x+5y-z=-20
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Subtract eq. 1 from eq. 2,
4x-5y%2B4z%2Bx%2B5y%2B5z=19-2
3.5x%2B9z=17
.
.
Add eq. 1 to eq. 3,
-x-5y-5z%2Bx%2B5y-z=2-20
-6z=-18
z=3
Then from eq. 3,
5x%2B9%283%29=17
5x=-10
x=-2
Then from eq. 3,
-2%2B5y-3=-20
5y=15
y=3