van=facebook.com/LearningCalculus$

f(a,b,c):=(a^2*b+b^2*c+c^2*a)*(a*b^2+b*c^2+c*a^2)=9*a^2*b^2*c^2 + k;

limit(limit(limit(f(a,b,c),a,0,plus),b,0,plus),c,0,plus);

f(x,y,z);