f(x)=a(x^2+1)-(2x+1/a),a>0最小值为a-2/a=-1,a=1f(x)=x^2-2x,sn=f(n)=n^2-2nn>=2,an=sn-s(n-1)=2n-3n=1,a1=s1=-1an=2n-3,a2n=4n-3,a2+a4+……+a2n=(2n-1)nbn=(a2+a4+……+a2n)/n=2n-1b(n+1)-bn=2所以bn是等差数列...