1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/20 11:09:32
![1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40](/uploads/image/z/20986-34-6.jpg?t=1%2F1%C3%972%2B1%2F2%C3%973%2B1%2F3%C3%974%2B1%2F4%C3%975%2B...%2B1%2F39%C3%9740)
1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40
1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40
1/1×2+1/2×3+1/3×4+1/4×5+...+1/39×40
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