y=(x^2-2x+1)/3(x-5/3)=[(x-5/3)^2 + 4/3(x-5/3) + 4/9] /3(x-5/3)=1/3[(x-5/3) + 4/9(x-5/3) + 4/3]>=1/3(4/3+4/3)>=8/9故当x=7/3时有最小值8/9不好意思啊!我自己算错了,方法是正确的!中间的(x-5/3)+4/9(x-5/3)是>=...