1⼀1×2+1⼀2×3+1⼀3×4+1⼀4×5+...+1⼀39×40 计算的过程

2025-01-02 12:41:37
推荐回答(1个)
回答1:

1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40
=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/39-1/40
=1-1/40
=39/40