问题 解答题

过点(2,3)的直线L被两平行直线L1:2x-5y+9=0与L2:2x-5y-7=0所截线段AB的中点恰在直线x-4y-1=0上,求直线L的方程.

答案

设线段AB的中点P的坐标(a,b),由P到L1、L2的距离相等,

|2a-5b+9|
22+52
=
|2a-5b-7|
22+52

经整理得,2a-5b+1=0,

又点P在直线x-4y-1=0上,所以a-4b-1=0

解方程组

2a-5b+1=0
a-4b-1=0

a=-3
b=-1

即点P的坐标(-3,-1),

又直线L过点(2,3)

所以直线L的方程为

y-(-1)
3-(-1)
=
x-(-3)
2-(-3)

即4x-5y+7=0.

直线L的方程是:4x-5y+7=0.

阅读理解

阅读理解。

     It was about eight o'clock in the morning. Jane was on her way to school. She was walking on 

Prince Road. Suddenly, she saw a small blue car coming very fast. When the red light was on, the river 

wanted to stop but he could not; The car crashed into a lamp post on the pavement.    

     Jane saw that the driver was badly hurt. Blood was coming out of his head. He was in great pain. 

Jane was frightened. She quickly went to telephone the police. Soon a police car and an ambulance arrived. The policemen helped the driver get out of his car. Then the ambulance took him to hospital.    

     A police inspector went up to Jane and invited her to the police station. He wanted Jane to tell him

 about the accident.

1. When did the accident happen?

                                                                             

2.What did Jane see after the accident happened?

                                                                             

根据短文内容;判断正(T)误(F)。

(    )3. The driver didn't stop his car.

(    )4. Jane was too frightened to move.

     翻译下面的句子。

5. The car crashed into a lamp post on the pavement.  

   _____________________________________                                                                         

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