设整数n>=2,正实数x1,x2,……xn满足(x1+x2+……xn)(1/x1+1/x2+……1/xn)=n^2+1

设整数n>=2,正实数x1,x2,……xn满足(x1+x2+……xn)(1/x1+1/x2+……1/xn)=n^2+1求证：（x1^2+x2^2+……+xn^2）(1/x1^2+1/x2^2+……+1/xn^2)>=n^2+4+2/n(n-1)