函数f（x）=x2-2lnx的单调减区间是（） A．（0，1] B．[1，+∞

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问题选择题

函数f（x）=x²-2lnx的单调减区间是（　　）

A．（0，1]

B．[1，+∞）

C．（-∞，-1]及（0，1]

D．[-1，0）及（0，1]

答案

求出函数f（x）=x²-2lnx的导数：

f/(x) =2x-

2(x+1)(x-1)

而函数的单调减区间就是函数的导数小于零的区间

由f^/=（x）＜0，得（-1，1）

因为函数的定义域为（0，+∞）

所以函数的单调减区间为（0，1]

故选A

阅读理解

阅读短文，选择正确的一项。

I have two new teachers. They are my math teacher and English teacher. My math teacher is short and

strong. He's very funny. My English teacher is from Canada. She's a university student. She's active and smart.

She's tall. We all like her.

1. I have ____________ new teachers.

A. 1

B. 2

C. 3

2. Who's your new teacher?

A. Math teacher and English teacher.

B. English teacher.

C. Chinese teacher.

3. What's your math teacher like?

A. He's tall.

B. He's very funny.

C. He's short and strong.

4. Do you like your English teacher?

A. Yes, we do.

B. No, we don't.

C. Yes, you do.

单项选择题

还处于控制性详细规划探索期间，所做的工作涉及的是（）。

A．规范化

B．基本定型

C．用于城市规划管理

D．尝试