1x2+2x3+3x4+4x5+5x6.......2017x2018

2025-01-05 23:35:33
推荐回答(1个)
回答1:

1x2+2x3+…+n(n+1)=n(n+1)(n+2)/3

然后N=2017
代入计算
得到答案

给好评哦