任意3个正数a、b、c,a+b+c+(abc)^(1/3) = (a+b)+[c+(abc)^(1/3)] ≥ 2(ab)^(1/2)+2[c^(2/3)]*(ab)^(1/6) ≥ 4(abc)^(1/3),当且仅当 a=b,c=(abc)^(1/3),(ab)^(1/2)=[c^(2/3)]*(ab)^(1/6) 时,即 a=b=c 时 等号都成立,...