x+2y+3z=-1 -x+y+3z=4 2x-y-z=-4

x+y+3z=-1...(i)
-x+y+3z=4...(ii)
2x-y-z=-4....(iii)
*eliminasi pers i dan ii
x+2y+3z=-1
-x+y+3z=4   
  2x+y=-5...(iv)
*eliminasi pers i dan iii
x+2y+3z=-1 | 1
2x -y - z =-4 | 3
x+2y+3z=-1
6x-3y-3z=-12 +
     7x-y=-13
*eliminasi pers iv dan v
2x+y=-5
7x-y=-13 +
   9x=-18
    x=-18/9
    x=-2
*x=-2 substitusikan ke pers iv
7x - y =-13
7.(-2)-y=-13
-14-y =-13
    -y =-13+14
    -y=1
     y=-1
*x=-2 dan y=-1 substitusikan ke pers i
x + 2y + 3z = -1
-2+2.(-1)+3z=-1
-2+(-2)+3z=-1
-4+3z=-1
  3z=-1+4
 3z=3
 z=1