a, b, c, d, e, f, g, h, i, j, l, r, 
2*a*h*i+b*h^2+2*c*d*j-c*e*i-c*g*h-d*e*h
a*i^2+2*b*h*i+2*c*f*j-c*g*i+d^2*j-d*e*i-d*g*h-e*f*h
b*i^2-d*g*i+2*d*j*r-e*i*l-f*g*h
f*(f*j-g*i)
