2xz-2xyz+ln(xyz)=0
2zdx+2xdz-2yzdx-2x(yz)'+1/xyz*(yzdx+x(yz)')
2zdx+2xdz-2yzdx-2xzdy-2xydz+1/xyz*(yzdx+xzdy+xydz)=0
(2z-2yz+yz/xyz)dx+(xz/xyz-2xz)dy+(2x-2xy+xy/xyz)dz=0
(2z-2yz+1/x)dx+(1/y-2xz)dy+(2x-2xy+1/z)dz=0;
dz=-2z-2yz+1/x)dx/(2x-2xy+1/z)+(2xz-1/y)dy/(2x+2xy+1/z)