1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)=?要用方法!

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/09 09:51:12
1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)=?要用方法!

1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)=?要用方法!
1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)=?
要用方法!

1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)=?要用方法!
1/(1×2×3)+1/(2×3×4)+1/(3×4×5)+.+1/(98×99×100)
=1/2 × [1/(1×2) - 1/(2×3) + 1/(2×3)-1/(3×4)+ 1/(3×4)-1/(4×5)+.+ 1/(98×99)-1/(99×100)]
=1/2 × [1/(1×2) - 1/(99×100)]
=1/2 × [1/2 - 1/9900]
=1/2 × 4949/9900
=4949/19800