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组合数怎么算了C(上是7)(下是9)得到什么数了?

2008-02-15 22:16:53t***
C(上是7)(下是9)得到什么数了?组合数怎么算了C(上是7)(下是9)得到什么数了?:C(m,n) =m!/(m-n)!n! C(7,9) =9!/(9-7)!7! =9*8/2! =36?

最佳回答

  • C(m,n) =m!/(m-n)!n! C(7,9) =9!/(9-7)!7! =9*8/2! =36
    2008-02-15 23:32:21
  • C(上是7)(下是9)=C(上是2)(下是9) =9*8/1*2=36
    2008-02-16 13:40:50
  • 很赞哦! (180)