(x^3/(13x² 5y²)*1/4000 3999/4000*(x y z)*1/54)(y^3/(13y^2 5z^2)*1/4000 3999/4000*(x y z)*1/54)(z^3/(13z^2 5x^2)*1/4000 3999/4000*(x y z)*1/54)-(x y z)^3/54^3,x=a,y=a u,z=a v