你没交代清,若只是n-->无穷,则:
lim n^2(1/n-1/(n+1)+1/n-1/(n+2)+1/n-1/(n+3)+...+1/n-1/(n+k))
化简一下为:
lim n/(n+1)+2n/(n+2)+...kn/(n+k)
=1+2+...+k
=k(k+1)/2
你没交代清,若只是n-->无穷,则:
lim n^2(1/n-1/(n+1)+1/n-1/(n+2)+1/n-1/(n+3)+...+1/n-1/(n+k))
化简一下为:
lim n/(n+1)+2n/(n+2)+...kn/(n+k)
=1+2+...+k
=k(k+1)/2