K789 :

 b^6*c^6*x^2*y - a^2*b^2*c^8*x^2*y - a^6*c^6*x*y^2 + a^2*b^2*c^8*x*y^2 + a^2*b^8*c^2*x^2*z - b^6*c^6*x^2*z - a^8*b^2*c^2*y^2*z + a^6*c^6*y^2*z + a^6*b^6*x*z^2 - 
     a^2*b^8*c^2*x*z^2 - a^6*b^6*y*z^2 + a^8*b^2*c^2*y*z^2 = 0