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1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?

来源:学生作业帮 编辑:拍题作业网作业帮 分类:数学作业 时间:2024/04/27 17:21:46
1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
等于多少?
1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)+1/(9*10)
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=1/2-1/10
=2/5