重酬!! SUPER EASY MATHS (好趕ga)

👨🏻‍🏫 學術台數學

Keiis

2011-01-08 3:21 am

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更新1:

For question 3, the last 2 steps, why the ans is (r+1)!, but not (r!)(r+1)??? Please explain...

回答 (2)

用戶9112

2011-01-08 3:35 am

✔ 最佳答案

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2011-01-10 21:25:53 補充：
(r+1)! = (r+1)(r)(r-1)(r-2)...(3)(2)(1)
=(r+1)(r!)

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[匿名]

2011-01-08 4:04 am

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