a1,a2,a3.an均为正数有a1+a2+a3+...+an>=n*(a1*a2*a3*..*an)^(1/n)a(1/b+1/c)+b(1c/+1/a)+c(1/a+1/b) =(a^2b+a^2c+b^2a+b^2c+c^a+c^2b)/abc >=6(a^2b*a^2c*b^2a*b^2c*c^2a*c^2b)^(1/6)/(abc) =6[(abc)^6]^(1/6)/(abc...