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$$n$$ is the number of $$8$$-digit positive integers consisting only of the digits $$1$$ and $$2$$, where the digit $$1$$ appears three times and the digit $$2$$ appears five times.
$$r$$ is the number of combinations of $$8$$ different letters taken $$3$$ at a time.
$$r$$ is the number of combinations of $$8$$ different letters taken $$3$$ at a time.
Quantity A
$$n$$
Quantity B
$$r$$
C显示答案
· 相关考点
6.3.7 密西西比法
6.3.7 密西西比法
以上解析由 考满分老师提供。
