$\binom{n+m}{n}=\binom{n+m}{m}.$
by yukimianyan @ 2022-11-22 12:05:25
对
by ZHOUziyang0221 @ 2022-11-22 12:09:38
@[yukimianyan](/user/509229)
等等大佬我有点儿迷糊了
题目里面给的不是 $n$ 在上 $n+m$ 在下吗?
by _farawaystar_ @ 2022-11-22 12:13:45
@[ZHOUziyang0221](/user/719516)
by _farawaystar_ @ 2022-11-22 12:13:57
@[_farawaystar_](/user/370037)
$$C_a^b =\binom ab$$
by peaneevall_kalaa @ 2022-11-22 12:15:04
@[zhouershan](/user/615348) 哦哦哦好的谢谢大佬们
by _farawaystar_ @ 2022-11-22 12:16:28
@[zhouershan](/user/615348)
大佬那么按题意来说, $n$ 个里面怎么可能取出 $n+m$ 个数呢?
by _farawaystar_ @ 2022-11-22 12:18:27
@[_farawaystar_](/user/370037) $C_b^a$ 表示在 $b$ 个球中取 $a$ 个。
by peaneevall_kalaa @ 2022-11-22 12:20:49
@[zhouershan](/user/615348) 哦对对不起
被我同学乱叫给搞迷糊了
谢谢大佬
by _farawaystar_ @ 2022-11-22 12:22:02