f′(x)>0 增、f′(x)<0 减；极值与最值看单调性与端点。
In the casino game called roulette, a common bet is to place a bet on red or black. If the ball lands on the chosen c…
十个筹码上场，赢到一百个就走。赌局略不利——每局赢面不到二分之一。
