题干

已知定义在R上的函数f(x)满足:f(x)=x2+2,x[0,1)2-x2,x[-1,0)且f(x+2)=f(x),g(x)=
2
x
+
5
x
+
2
,则方程f(x)=g(x)在区间[﹣5,1]上的所有实根之和为(  )

A:﹣8 

B:﹣7

C:﹣6

D:0

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答案(点此获取答案解析)

B

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    What a lesson for me! It was August and it was hot. I had to wear a tie to do a survey door by door in this neighbourhood, but I was always refused. I finally caught on and began with “Before you close the door, I am not selling anything and I just need to ask a few questions about yourself and the community”.

    The young woman inside the doorway stopped for a moment, confused by my rude introduction and finally said, “Sure. Come on in. Don't mind the mess. It's hard to keep up with my kids.”

    “I just need to ask a few questions about yourself and your family. Although this may sound personal, I won't need to use your names. This information will be used.” She interrupted me. “Would you like a glass of cold water? You look like you've had a rough day.” “Why yes!” I said gratefully. Just as she returned with the water, a man came walking in the front door. It was her husband. “Joe, this man is here to do a survey.” I stood and politely introduced myself.

    “Joe works for the town,” she said. “What do you do?” I asked. She jumped right in not letting him answer. “Joe collects garbage. You know I'm so proud of him.”

    There was a silence. I didn't know what to say. I shook my head searching for the right words. “That's unbelievable! Most people would not be satisfied with a job like that. It certainly is a difficult one. But your attitude about it is amazing.” I said.

    She walked over to the shelf. As she returned she held a small framed(装裱)paper, walking toward Joe. “I have always been proud of him and always will be. You see I don't think the job makes the man, but the man makes the job!” she said as she handed me the paper.

    It said: If a man is called to be a cleaner, he should clean streets so well that all the hosts of heaven and earth will pause to say, “Here lived a great cleaner who did his job well.”