回復 5# Exponential 的帖子
把A都分離開來下去做
有錯還請指教
\(\displaystyle \frac{6!}{3!2!}\times\textrm{C} _{4}^{7}\)-\((\frac{5!}{2!}\times\textrm{C} _{4}^{6}-\frac{4!}{2!}\times\textrm{C} _{4}^{5})\)-\((\frac{5!}{3!}\times\textrm{C} _{4}^{6})\)+\((4!\times\textrm{C} _{4}^{5}-3!\times\textrm{C} _{4}^{4})\)
瑋岳老師已經先早一步回覆了XD
