由二次函数y=（2x-1）（x+2）+1的图象如何平移，可得到y=2x2的图象（_爱下问搜题

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问题选择题

由二次函数y=（2x-1）（x+2）+1的图象如何平移，可得到y=2x²的图象（　　）

A．向左移动

3

4

个单位，向上移动

17

8

个单位

B．向左移动

3

4

个单位，向下移动

17

8

个单位

C．向右移动

3

4

个单位，向上移动

17

8

个单位

D．向右移动

3

4

个单位，向下移动

17

8

个单位

答案

二次函数y=（2x-1）（x+2）+1整理为：y=2（x+

3

4

）²-

17

8

，

根据“左加右减，上加下减”的原则可知，可将该抛物线向右平移

3

4

个单位，向上平移

17

8

个单位后得到y=2x²．

故选C．

选择题

下列说法正确的是（　　）

A．加速度大，速度一定大

B．速度大，加速度一定大

C．速度变化量越大，加速度越大

D．速度变化越快，加速度越大

完形填空

On August 26, 1999, New York City experienced a torrential downpour. The rain caused the streets to ____ and the subway system almost came to a stop.
Unfortunately, this happened during the morning rush hour. Many people who were going to work were ____ to go home. Some battled to ____ a taxi or to get on a bus. Still others faced the ____ bravely, walking miles to get to work.
I ____ to be one of the people on the way to work that morning. I went from subway line to subway line only to find that most ____ had stopped. After making my way ____ crowds of people, I finally found a subway line that was ____. Unfortunately, there were so many people waiting to ____ the subway that I could not even get down the stairs to the ____. So I took the train going in the opposite direction, and then switch back to the downtown train. Finally, after what seemed like a forever, the train ____ my stop. Then I had to walk several blocks in the increasingly heavy rain. When I finally got to my office, I was ____ through, exhausted and ____.
My co-workers and I spent most of the day drying off. When it was 5:00 pm，I was ready to go home. I was about to turn off my computer ____ I received an email from Garth, my Director:
I would like to thank all of you who made the effort and __ __ reported to work. It is always reassuring(令人欣慰), at times like these, when employees so clearly show their ____ to their jobs. Thank you.
Garth’s email was short, but I learned more from that ____ message than I ever did from a textbook. The email taught me that a few words of ____ can make a big difference. The rainstorm and the traffic ____ had made me tired and upset. But Garth’s words immediately____ me and put a smile back on my face.

B．discouraged

B．appreciation