lim(n→∞)∑(n,k=1)((-1)^(k-1))⼀k 就是1-1⼀2+1⼀3-1⼀4... 要详细步骤,有几种解法给几种,在线等

2025-01-02 08:37:44
推荐回答(1个)
回答1:

Xn=∑1/[k(K+1)(k+2)]=1/2∑(1/k-2/(k+1)+1/(k+2))
=1/2∑[(1/k-1/(k+1))-(1/(k+1)-1/(k+2))]
=1/4