Question 139013
x-y-z=0 multiply this equation by 2 & add to the third equation.  
x-2y-2z=3
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-2x+2y-z=3
2x-2y-2z=0 now add.
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-3z=3
z=3/-3
z=-1 answer.
x-y+1=0
x-2y+6=3 now multiply this equation by -1 & add to the previous equation.
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x-y+1=0
-x+2y-6=-3 now add.
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y-5=-3
y=-3+5
y=2 answer.
x-2+1=0
x-1=0
x=1 answer.