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概率计算:C下面5上面3/C下面7上面2怎么算急
概率计算:C下面5上面3/C下面7上面2怎么算急
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2020-05-08 17:51
概率计算:C下面5上面3/C下面7上面2怎么算急
概率计算:C下面5上面3/C下面7上面2怎么算急
[(5×4×3)/(3×2×1)]/[(7×6)/(2×1)]=10/21
C下面5上面3=[(5×4×3)/(3×2×1)]
C下面7上面2=[(7×6)/(2×1)]