1/3*5+1/5*7+1/7*9+1/9*11+1/11*13+1/13*15
答案:4 悬赏:0 手机版
解决时间 2021-04-15 06:48
- 提问者网友：我没有何以琛的痴心不悔
- 2021-04-14 16:32
1/3*5+1/5*7+1/7*9+1/9*11+1/11*13+1/13*15
最佳答案
- 五星知识达人网友：十年萤火照君眠
- 2021-04-14 17:44
解原式=1/2*(2/3*5+2/5*7+.....+2/13*15)
=1/2(1/3-1/5+1/5-1/7+....+1/13-1/15)
=1/2*(1/3-1/15)
=1/2*(4/15)
=2/15
=1/2(1/3-1/5+1/5-1/7+....+1/13-1/15)
=1/2*(1/3-1/15)
=1/2*(4/15)
=2/15
全部回答
- 1楼网友：轻熟杀无赦
- 2021-04-14 21:54
- 2楼网友：零点过十分
- 2021-04-14 20:32
1/1*3+1/3*5+1/5*7+1/7*9+1/9*11+1/11*13+1/13*15
=1/2*(1-1/3+1/3-1/5+...+1/13-1/15)
=1/2*(1-1/15)
=1/2*14/15
=7/1追答7/15
=1/2*(1-1/3+1/3-1/5+...+1/13-1/15)
=1/2*(1-1/15)
=1/2*14/15
=7/1追答7/15
- 3楼网友：天凉才是好个秋
- 2021-04-14 19:10
1/3*5+1/5*7+1/7*9+1/9*11+1/11*13+1/13*15
=1/2*(1/3-1/5)+2*(1/5-1/7)+2*(1/7-1/9)+....2*(1/13-1/15)
=1/2*(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13+1/13-1/15)
=1/2*(1/3-1/15)
=1/2*(5/15-1/15)
=1/2*(4/15)
=2/15
=1/2*(1/3-1/5)+2*(1/5-1/7)+2*(1/7-1/9)+....2*(1/13-1/15)
=1/2*(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13+1/13-1/15)
=1/2*(1/3-1/15)
=1/2*(5/15-1/15)
=1/2*(4/15)
=2/15
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