1/12+1/23+1/34+1/45+...1/39*40怎么计算?

分类: 作业答案 • 2022-02-10 23:49:12

问题描述：

1/1*2+1/2*3+1/3*4+1/4*5+...1/39*40怎么计算?

答

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

1/1*2+1/2*3+1/3*4+1/4*5+...1/39*40怎么计算?