From 97b84e91dba8cb55dc68c2c4025edcf98483799c Mon Sep 17 00:00:00 2001 From: Zhao Xin <7176466@qq.com> Date: Sun, 21 Jan 2024 19:57:14 +0800 Subject: [PATCH] =?UTF-8?q?=E6=9B=B4=E6=96=B0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- 概念/排列与组合.md | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/概念/排列与组合.md b/概念/排列与组合.md index 0ee839a..ea0c49b 100644 --- a/概念/排列与组合.md +++ b/概念/排列与组合.md @@ -10,4 +10,6 @@ $$ \begin{align} A_{10}^3 &= \underbrace{10\times9\times8}_{3个} = 720 \newline A_n^n &= \underbrace{n\times(n-1)\times(n-2)\times\cdots\times1}_{n个} = n! (A_n^n叫全排列,n!叫做n的阶乘) \newline A_{n}^{m} &= \underbrace{n\times(n-1)\times(n-2)\times\cdots\times(n-m+1)}_{m个} \newline &= \dfrac{n\times(n-1)\times(n-2)\times\cdots\times(n-m+1)\times(n-m)\times(n-m-1)\times(n-m-2)\times\cdots\times1}{(n-m)\times(n-m-1)\times(n-m-2)\times\cdots\times1} \newline &= \dfrac{n!}{(n-m)!} \end{align}$$ -公式1:$ A_n^n = n! $ +公式1:$ \boxed{ A_n^n = n! } $ + +公式2:$ \boxed{ A_n^m = \dfrac{n!}{(n-m)!} } $