K787 :

 a^4*b^4*c^4*x^2*y - b^6*c^6*x^2*y - a^4*b^4*c^4*x*y^2 + a^6*c^6*x*y^2 - a^4*b^4*c^4*x^2*z + b^6*c^6*x^2*z + a^4*b^4*c^4*y^2*z - a^6*c^6*y^2*z - a^6*b^6*x*z^2 + 
     a^4*b^4*c^4*x*z^2 + a^6*b^6*y*z^2 - a^4*b^4*c^4*y*z^2 = 0