2/3+2/15+2/35+2/63+2/99+2/132
答案:3 悬赏:50 手机版
解决时间 2021-01-24 14:52
- 提问者网友：富士山上尢
- 2021-01-24 04:29
2/3+2/15+2/35+2/63+2/99+2/132
最佳答案
- 五星知识达人网友：酒者煙囻
- 2021-01-24 05:21
原式=2/(1x3)+2/(3x5)+2/(5x7)+2/(7x9)+2/(9x11)+2/(11x12)
=(3-1)/(1x3)+(5-3)/(3x5)+(7-5)/(5x7)+(9-7)/(7x9)+(11-9)/(9x11)+2/(11x12)
=(1-1/3)+(1/3-1/5)+(1/5-1/7)+(1/7-1/9)+(1/9-1/11)+2/(11x12)
=1+(1/3-1/3)+(1/5-1/5)+(1/7-1/7)+(1/9-1/9)-1/11+2/(11x12)
=10/11+2/(11x12)
=(120+2)/(11x12)
=61/66.
=(3-1)/(1x3)+(5-3)/(3x5)+(7-5)/(5x7)+(9-7)/(7x9)+(11-9)/(9x11)+2/(11x12)
=(1-1/3)+(1/3-1/5)+(1/5-1/7)+(1/7-1/9)+(1/9-1/11)+2/(11x12)
=1+(1/3-1/3)+(1/5-1/5)+(1/7-1/7)+(1/9-1/9)-1/11+2/(11x12)
=10/11+2/(11x12)
=(120+2)/(11x12)
=61/66.
全部回答
- 1楼网友：第四晚心情
- 2021-01-24 07:03
13分之12
- 2楼网友：迟山
- 2021-01-24 06:21
2/3+2/15+2/35+2/63+2/99+2/132
=1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13
=1-1/13
=12/13
=1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13
=1-1/13
=12/13
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