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问题 选择题

函数g（x）=x3+mx2+nx+m2在x=1处有极值10，则m，n的值是（　　）

A．m=-11，n=4

B．m=4，n=-11

C．m=-4，n=11

D．m=11，n=-4

答案

∵g（x）=x3+mx2+nx+m2∴g′（x）=3x2+2mx+n

依题意可得

g(1)=10
g′(1)=0
⇒
1+m+n+m2=10
3+2m+n=0        
联立可得
m=4
n=-11
或
m=-3
n=3

当m=-3，n=3时，f′（x）=3x2-6x+3=3（x-1）2≥0，函数在R上单调递增，函数无极值，舍

故选B．

阅读理解

阅读短文，回答问题。

      Good morning, boys and girls! I'm John. This is my family. Look, this is my mother. She is a teacher. She

likes music. This is my father. He is 42. He is a driver. This is my grandpa. He is 68. He is a farmer. This is my

grandma. She is 65. She was a nurse. This is my uncle. He is 37. He likes sports and science.

1. What's John's mother?

________________________________________________________

2. How old is John's father?

________________________________________________________

3. What's John's grandpa?

________________________________________________________

4. What does John's uncle like?

________________________________________________________

5. How many people are there in John's family?

________________________________________________________
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单项选择题

漏出液中的LD与血清LD的比值常（）

A.<0.6

B.<0.5

C.<0.4

D.<0.3

E.<0.1
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