can you help me check my work?

[jferrel8]

solve for,
1x+1y+1z=4
1x-2y-1z=1
2x-1y-2z= -1

first, 2(1x+1y+1z=4)
and i got....
2x+2y+2z=8
1x-2y-1z=1
....i got 3x+1z=9

second, -2(2x-1y-2z= -1)
and i got...
1x-2y-1z=1
-4x+2y+4z=2
...i got -3x+3z=3....so.....
3x+1z=9
-3x+3z=3...i got z=3

third, i plugged z=3 into...
-3x+3(3)=3 and i got x=2
so....
2(2)-1y-2(3)= -1 and i got y=-1

therefore, the solution equals (2,-1,3)

 

[Loren]

1x+1y+1z=4
1x-2y-1z=1
2x-1y-2z= -1
therefore, the solution equals (2,-1,3)

Plugging in your result we have...

1(2)+1(-1)+1(3)=4 >>> 2-1+3=4 >>> true
1(2)-2(-1)-1(3)=1 >>> 2+2-3=1 >>> true
2(2)-1(-1)-2(3)= -1 >>> 4+1-6=-1 >>> true

Your answer checks. Nice going.