1/1*2+1/2*3+1/3*4+1/4*5+...1/39*40怎么计算?_数学解答

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

人气：364 ℃　时间：2020-01-29 09:45:18

解答

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