梦想世界除魔下腰带:1/2+5/6+11/12+19/20+29/30……9899/990=?

来源:百度文库 编辑:高校问答 时间:2024/04/29 00:33:37
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1/2+5/6+11/12+19/20+29/30+...+9701/9702+9899/9900
=1/2+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+……+(1-1/9702)+(1-1/9900)
=1/2+[1-(1/2-1/3)]+[1-(1/3-1/4)]+[1-(1/4-1/5)]+[1-(1/5-1/6)]+……+[1-(1/98-1/99)]+[1-(1/99-1/100)]
=1*100+1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+……1/98-1/98+1/99-1/99+1/100
=100+1/100
=100又1/100

题目给错了,最后应该是9900,
1/2+5/6+11/12+19/20+29/30+...+9701/9702+9899/9900
=1/2+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+……+(1-1/9702)+(1-1/9900)
=1/2+[1-(1/2-1/3)]+[1-(1/3-1/4)]+[1-(1/4-1/5)]+[1-(1/5-1/6)]+……+[1-(1/98-1/99)]+[1-(1/99-1/100)]
=1*100+1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+……1/98-1/98+1/99-1/99+1/100
=100+1/100
=100又1/100

1/2+5/6+11/12+19/20+29/30+...+9701/9702+9899/9900
=1/2+(1-1/6)+(1-1/12)+(1-1/20)+(1-1/30)+……+(1-1/9702)+(1-1/9900)
=1/2+[1-(1/2-1/3)]+[1-(1/3-1/4)]+[1-(1/4-1/5)]+[1-(1/5-1/6)]+……+[1-(1/98-1/99)]+[1-(1/99-1/100)]
=1*100+1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+……1/98-1/98+1/99-1/99+1/100
=100+1/100
=100又1/100