m^2+n^2+[m^2+(1-n)]^(1/2)+[(1-m)^2+n^2]^(1/2)+[(1-m)^2+(1-n)^2]然后你看啊,m^2+n^2>=2mn为什呢,因为(m-n)^2>=0 当且仅当m=n时成立.（1）同理[m^2+(1-n)]^(1/2)>=[2m(1-n)]^(1/2)当且仅当m=1-n时成立.（2）[(1-m)...