K987 :

a b^3 c^5 x^2 y-b^2 c^7 x^2 y-a^3 b c^5 x y^2+a^2 c^7 x y^2+b^7 c^2 x^2 z-a b^5 c^3 x^2 z-a^7 c^2 y^2 z+a^5 b c^3 y^2 z-a^2 b^7 x z^2+a^3 b^5 c x z^2+a^7 b^2 y z^2-a^5 b^3 c y z^2=0