1/3*5+1/5*7+1/7*9+1/9*11+1/11*13
＝1/2×﹙1/3－1/5＋1/5－1/7＋1/7－1/9＋1/9－1/11＋1/11－1/13﹚
＝1/2×﹙1/3－1/13﹚
＝1/2×10/39
＝5/39.
计算:1/3*5+1/5*7+1/7*9+1/9*11+1/11*13
计算:1/3*5+1/5*7+1/7*9+1/9*11+1/11*13
数学人气：204 ℃时间：2019-10-19 10:50:20
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