题干

在实数的原有运算法则中,我们补充定义新运算“”如下:当ab时,ab=a;当a<b时,ab=b2。则函数fx=1x·x-2xlnxx(0,2]有(    )(“·”和“-”仍为通常的乘法和减法)

A:最大值为8-2ln2,无最小值

B:最大值为8-2ln2,最小值为1

C:无最大值,无最小值

D:无最大值,最小值为1

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答案(点此获取答案解析)

D

同类题2

baby   car   enough    leave     anything    us
poor   rich   remember   surprised   took        whenever

    One a snowy evening, a rich lady was standing by the road. She was very worried. Her____ had broken down. Just then a poor man named Robert came. He was on his way back home from work as usual.
    The lady thought, “Is the man going to help me? He looks very cold and hungry. ”But to her ____ , he stopped and said with a smile, “What’s wrong, madam?” The lady told him what was happening.
    After forty minutes, the car was at last fixed by Robert. The lady wanted to pay him.
  “No, that’s ____  , madam.” he said, “I was just helping someone in need. If you really want to pay me back, I hope you ____ see someone in trouble, please give him a hand.” A few minutes later, the lady saw a shabby house by the road. She  ____  Robert's words, so she stopped. The hostess warmly asked her in. The lady could see that was a ____  family and they needed help. When the hostess was making tea in the kitchen, the lady ____ 500 dollars on the table and went away quietly. Robert came home later than before, thinking how hard their life was. Their ____  was to be born the next month but there wasn't ____  money. His wife went up to him, gave him a kiss and said softly, “Don't worry, dear! Everything’s going to be all right. A stranger has helped us out. ”
Let's always be ready to help others because helping others is helping ____  .