2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?快给好2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?..

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/29 17:37:19
2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?快给好2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?..
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2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?快给好2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?..
2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?快给好
2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?..

2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?快给好2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)过程是?..
1/n(n+2)=1/2(1/n-1/(n+2))
2(3/5×7+3/7×9+3/9×11+3/11×13+3/13×15)
=2*3*(1/5*7+1/7*9+1/9*11+1/11*13+1/13*15)
=3*(1/5-1/15)=2/5