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问题 选择题

集合M={x|x2-2x-3＜0}，N={x|2x-2＞0}，则M∩N等于（　　）

A．（-1，1）

B．（1，3）

C．（0，1）

D．（-1，0）

答案

由集合M中的不等式x2-2x-3＜0，

因式分解得：（x-3）（x+1）＜0，

可化为：

x-3＞0
x+1＜0
或
x-3＜0
x+1＞0
，

解得：-1＜x＜3，

∴M={x|-1＜x＜3}，

由集合N中的不等式2x-2＞0，解得：x＞1，

∴N={x|x＞1}，

则M∩N={x|1＜x＜3}=（1，3）．

故选B

单项选择题

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Ideally, the password should be something (5) could guess. In practice, most people choose a password that is easy to remember, such as their name or their initials. This is one reason it is relatively easy to break into most computer system.

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