[理工][離散]99台大工科 排列組合
In how many ways can we distribute 8 red balls and 9 blue balls among
6 children so that each child receives at least one blue ball?
解答是這樣
13! 8!
--------- * -------
8!5! 3!5!
看懂解答意思
不過如果這樣想
每人先拿一藍色 剩下八個紅色 三個藍色去分
8個red 3個blue 5個| <---|用來分成六等分
(8+3+5)!
---------------
8!3!5!
請問這樣錯在哪裡
thx
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