[math][(1/2x+2/3y+z)^2-(1/2+2/3y-z)^2+1/3yz]^2-3yz^2(4x+3y)[/math]
[math][1/4x^2+4/9y^2+z^2+2/3xy+xz+4/3yz-1/2x^2-4/9y^2-z^2-2/3xy+xz+4/3yz+1/3yz]^2-12xyz^2-9y^2z^2[/math]
[math][2xz+3yz]^2-12xyz^2-9y^2z^2[/math]
[math]4x^2z^2+12xyz^2+9y^2z^2-9y^2z^2-12xyz^2[/math]
[math]rx^2z^2[/math]
