1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)
=1-1/2+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
=1-1/9
=8/9
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72=?
3个回答
相关问题
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1／2 + 1／6 + 1／12 + 1／20 + 1／30+ 1／42 + 1／56 + 1／72＝
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1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72=?
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6/1+12/1+20/1+30/1+42/1+56/1+72/1=?
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1/6+1/12+1/20+1/30+1/42+1/56+1/72
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2\1-6\1-12\1-20\1-30\1-42\1-56\1-72\1-90\1
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1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
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2/1＋6/1＋12/1＋20/1＋30/1＋42/1＋56/1＋72/1＋90/1
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1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
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1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
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1.计算：1 - 1／2 - 1／6- 1／12 - 1／20 - 1／30 - 1／42 - 1／56 - 1／72