早教吧 育儿知识 作业答案 考试题库 百科 知识分享

lim(n/(n^2+1)+n/(n^2+2^2)+……+n/(n^2+n^2))n^2指n的平方

题目详情
lim(n/(n^2+1)+n/(n^2+2^2)+……+n/(n^2+n^2))
n^2 指n的平方
▼优质解答
答案和解析
lim(n/(n^2+1)+n/(n^2+2^2)+……+n/(n^2+n^2))
=lim1/n*[1/(1+1/n^2)+1/(1+(2/n)^2)+……+1/(1+(n/n)^2)]
根据定积分的定义.
对于∫1/(1+x^2) x∈(0,1)
=lim∑1/n*(1/(1+(i/n)^2)
=lim1/n*[1/(1+1/n^2)+1/(1+(2/n)^2)+……+1/(1+(n/n)^2)]
则lim(n/(n^2+1)+n/(n^2+2^2)+……+n/(n^2+n^2))
=lim1/n*[1/(1+1/n^2)+1/(1+(2/n)^2)+……+1/(1+(n/n)^2)]
=∫1/(1+x^2) x∈(0,1)
=arctanx x∈(0,1)
=π/4