點解r!(24-r)!/((r+2)!(24-r-2)!)
= (24-r)(24-r-1)/((r+1)(r+2))
5明呢步
find r!(24-r)!/((r+2)!(24-r-2)!)
2008-06-20 1:13 am
回答 (2)
2008-06-20 2:57 am
2008-06-20 1:22 am
r!(24-r)!/((r+2)!(24-r-2)!)
=r!(24-r)(24-r-1)(24-r-2)/(r+2)(r+1)(r)!(24-r-2)
=(24-r)(24-r-1)/(r+1)(r+2)
=r!(24-r)(24-r-1)(24-r-2)/(r+2)(r+1)(r)!(24-r-2)
=(24-r)(24-r-1)/(r+1)(r+2)
收錄日期: 2021-04-23 20:45:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080619000051KK01722