1X2X3+2X3X4+...+n(n+1)(n+2)等于多少呢

2025-01-07 19:24:39
推荐回答(1个)
回答1:

由1×2×3+2×3×4+。。。+n(n+1)(n+2)=n(n+1)(n+2)(n+3)/4.