搜搜做题作业网"1/2+1/6+1/12+1/20+1/30=.+1/90"这道题怎么写
来源：学生作业帮 编辑：搜搜做题作业网作业帮 分类：数学作业 时间：2024/06/30 21:18:12
"1/2+1/6+1/12+1/20+1/30=.+1/90"这道题怎么写
=1/1×2+1/2×3+1/3×4+……+1/9×10
=1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10
=1-1/10
=9/10
=1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10
=1-1/10
=9/10