lim(n->∞)∑(k=1,n)n/(n^2+k^2)
=∫n/(n^2+k^2)dk
=∫1/sec²x*sec²xdx (k=ntanx)
=∫dx
=x+C
=arctan(k/n)+C
=arctan1-arctan(1/n) n->+∞
=π/4-0
=π/4我是这样做出来了=∑(k=1,n)1/n*1/[1+(k/n)^2]=∫<1,0>1/(1+x^2)dx还是要谢谢你一个意思