2分之1+6分之1+加12分之1+20分之1+30分之1+42分之一等于几

分类: 作业答案 • 2021-12-19 18:29:33

问题描述：

答

你好,寒风烁烁
1/2+1/6+1/12+1/20+1/30+1/42
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7