题目

.已知函数． （1）判断函数在区间 上的单调性，并用定义证明你的结论； （2）求该函数在区间 上的最大值与最小值． 答案：【详解】（1）函数在 上是增函数． 证明：任取，且， 则 ． 易知，所以，即， 所以函数在上是增函数． （2）由（1）知函数在 上是增函数， 则函数的最大值为 ，最小值为。短文改错 假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。作文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。 增加：在缺词处加一个漏子符号（∧）并在其下面写出该加的词。 删除：在错的词下划一横线，并在该词下面写出修改后的词。 注意：1. 每处错误及其修改均仅限一词； 2. 只允许修改10处，多者（从第11处起）不计分。I had an argument with my friend Ben yesterday because his favorite movie, which I thought was not interested. After the argument, he went off without say goodbye to me. I was angry on him. In the afternoon I started to feel sad because he is my best friend. After school, I asked him if he wanted to go with me as usually. He gave me a strange look and turned away. But, this time, he does say goodbye to me quietly. Later, while I was watching TV at home, the phone rang. This was Ben and he said he was sorry for that he did. He felt like childish. I said never mind. Now I feel much better since we are still good friend.