x^2+y^2+z^2-2x+4y-6z+14=0
x^2-2x+1+y^2+4y+4+z^2-6z+9=0
(x-1)^2+(y+2)^2+(z-3)^2=0
x=1,y=-2,z=3
x+y-z=1-2-3=-4
x+y+z=1+(-2)+3=2
x+y-z/x+y+z=-4/2=-2