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![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/8/d3a1125f-6c48-4751-addf-bbb0214df997.png?resizew=262)
A.35 | B.36 | C.56 | D.70 |
3 . 卡特兰数是组合数学中一个常在各种计数问题中出现的数列.以比利时的数学家欧仁·查理·卡特兰(1814-1894)命名.历史上,清代数学家明安图(1692年-1763年)在其《割圜密率捷法》最早用到“卡特兰数”,远远早于卡塔兰.有中国学者建议将此数命名为“明安图数”或“明安图-卡特兰数”.卡特兰数是符合以下公式的一个数列:且
.如果能把公式化成上面这种形式的数,就是卡特兰数.卡特兰数是一个十分常见的数学规律,于是我们常常用各种例子来理解卡特兰数.比如:在一个无穷网格上,你最开始在
上,你每个单位时间可以向上走一格,或者向右走一格,在任意一个时刻,你往右走的次数都不能少于往上走的次数,问走到
,0≤n有多少种不同的合法路径.记合法路径的总数为
(1)证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686ece75006ad358f23314dc8a246e11.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686ece75006ad358f23314dc8a246e11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
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A.452 | B.848 | C.984 | D.1003 |
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/26/4cf3dc7b-b35f-48cc-9fad-ceab1ed82ed0.png?resizew=196)
A.![]() | B.![]() | C.![]() | D.![]() |
A.432种 | B.486种 | C.504种 | D.540种 |
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A.240 | B.360 | C.600 | D.720 |
8 . 《周易》包括《经》和《传》两个部分,《经》主要是六十四卦和三百八十四爻,它反映了中国古代的二进制计数的思想方法.我们用近代语解释为:把阳爻“”当做数字“1”,把阴爻“
”当做数字“0”,则六十四卦代表的数表示如下:
卦名 | 符号 | 表示的二进制数 | 表示的十进制数 |
坤 | 000000 | 0 | |
剥 | 000001 | 1 | |
比 | 000010 | 2 | |
观 | 000011 | 3 | |
… | … | … | … |
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/23/3b35ec01-dfaf-4789-964d-034149fc53c9.png?resizew=31)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/23/44197ce5-325f-4129-893f-2c1be8d182ae.png?resizew=31)
(2)若某卦的符号由四个阳爻和两个阴爻构成,求所有这些卦表示的十进制数的和;
(3)在由三个阳爻和三个阴爻构成的卦中任取一卦,若三个阳爻均相邻,则记5分;若只有两个阳爻相邻,则记2分;若三个阳爻均不相邻,则记1分.设任取一卦后的得分为随机变量X,求X的概率分布和数学期望.
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A.![]() | B.![]() | C.![]() | D.![]() |
A.1560种 | B.2160种 | C.2640种 | D.4140种 |