二胡江河水:极限问题10

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n趋于无穷时,lim(1/(n^2)+2/(n^2)+…+n/(n^2))=?
答案1/2

lim(1/(n^2)+2/(n^2)+…+n/(n^2))
=lim((1+2+3+...+n)/(n^2))
=lim((1+n)*n/(2n^2))
=lim((n^2+n)/(2n^2))
比较最高次项的系数,得lim(1/(n^2)+2/(n^2)+…+n/(n^2))=1/2