Question 331483
x+y+z=-1
x-y+3z=-17
2x+y+z=-2

adding the first two we eliminate y
2x+4z=-18
adding equations 2 and 3 we eliminate y
3x+4z=-19
now we have two equations and two unknowns
2x+4z=-18
3x+4z=-19    multiply (2x+4z=-18)*-1 and add

-2x-4z=18
3x+4z=-19   adding we eliminate z
x=-1    substitution 3(-1)+4z=-19
-3+4z=-19 add 3 to both sides
4z=-16    divide by 4
z=-4     substitution x=-1,z=-4 to the original
x+y+z=-1
-1+y-4=-1
-5+y=-1 add 5
y=4
(x,y,z)=(-1,4,-4) answer