定义法判单调:任取 x1<x2 比 f(x1) 与 f(x2) 大小;最值经单调性分析得出。
We have two urns, I and II. Urn I contains 2 black balls and 3 white balls. Urn II contains 1 black ball and 1 white …
两个罐子,随手挑一个,摸出一个黑球。问:这个球更可能来自哪个罐子?