考虑1改写题目,设loga=x logb=y logc=z 1y/x+z/y+x/z<= x/y+y/z+z/xy+x<=z+y(z-y)(y+x)(y-x)<=(z-y)(z+y)(y-x)(z-y)(y^2-x^2)<=(z^2-y^2)(y-x)z(y^2-x^2)-y(y^2-x^2)<=y(z^2-y^2)-x(z^2-y^2)z(y^2-x^2)+x(z^2-y^2)<=y(z^2-y^2)+y(y^2-x^2)z(y^2-x^2)+x(z^2-y^2)<=y(z^2-x^2)两边除xyz(y^2-x^2)/xy+(z^2-y^2)/zy<=(z^2-x^2)/xz(y/x-x/y=(y^2-x^2)/xy,其馀同理)y/x-x/y+z/y-y/z<=z/x-x/z移项得证y/x+z/y+x/z<=x/y+y/z+z/x