您的位置: 首页  >  作业答案  >  数学  >  1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?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

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

分类: 作业答案 • 2021-12-19 16:43:21
问题描述：

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

答

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解法是正确的.

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