听下面一段对话.回答第13-15题. W: Excuse me, Da Ming. It must be hard work as a secondary school student now. M: It certainly is. I'm going to have the most important examination. And I must get ready for every subject for it. W: I guess you can't have enough sleep. M: Yes. I have to get up at six o'clock every morning and go to bed very late. W: Why do you get up so early then? M: Because I want to remember and review something at that time. W: Does your mother get up at the same time as you? M: Yes, she cooks breakfast for me. She wants me to keep healthy. W: Your mother is so kind. Well, how do you spend your free time? M: Free time? I have no free time. I have lessons all the time. W: I really hope it goes well after your hard work. M: Thank you. 听短文.从所给选项中选出最佳答案. I went to town yesterday and decided to stop at the bank to see Alice Green. I thought she might have time to go to lunch with me. When I got to the bank, they told me that she had just been out for a few minutes. I asked them if she would be back by 11:30 or 11:45, and they said yes. I had some time. So I decided to wait for her. Then I walked over to some chairs by the windows and sat down. I decided to watch the front door because I knew she would come back in that way. I waited and waited, but she didn't come through that door. Finally I decided not to wait any longer. It was 12:30, and I was sure that she wouldn't be back until after lunch. I got up and as I started to walk towards the door, somebody called my name. I turned around and was surprised to find out that was Alice. When I said that someone had told me she had been out, she told me that she hadn't left her office all the morning. 查看更多

 

题目列表(包括答案和解析)

阅读理解题:一次数学兴趣小组的活动课上,师生有下面一段对话,请你阅读完后再解答下面问题:
老师:同学们,今天我们来探索如下方程的解法:(x2-x)2-8(x2-x)+12=0.
学生甲:老师,先去括号,再合并同类项,行吗?
老师:这样,原方程可整理为x4-2x3-7x2+8x+12=0,次数变成了4次,用现有的知识无法解答.同学们再观察观察,看看这个方程有什么特点?
学生乙:我发现方程中x2-x是整体出现的,最好不要去括号!
老师:很好.如果我们把x2-x看成一个整体,用y来表示,那么原方程就变成y2-8y+12=0.
全体同学:咦,这不是我们学过的一元二次方程吗?
老师:大家真会观察和思考,太棒了!显然一元二次方程y2-8y+12=0的解是y1=6,y2=2,就有x2-x=6或x2-x=2.
学生丙:对啦,再解这两个方程,可得原方程的根x1=3,x2=-2,x3=2,x4=-1,嗬,有这么多根啊.
老师:同学们,通常我们把这种方法叫做换元法.在这里,使用它最大的妙处在于降低了原方程的次数,这是一种很重要的转化方法.
全体同学:OK!换元法真神奇!
现在,请你用换元法解下列分式方程(
x
x-1
)2-5(
x
x-1
)-6=0

查看答案和解析>>

27、阅读下面一段材料,回答问题.
我国宋朝数学家杨辉在他的著作《详解九章算法》中提出右下表,此表揭示了(a+b)n(n为非负整数)展开式的各项系数的规律,例如:
(a+b)0=1,它只有一项,系数为1;
(a+b)1=a+b,它有两项,系数分别为1,1;
(a+b)2=a2+2ab+b2,它有三项,系数分别为1,2,1;
(a+b)3=a3+3a2b+3ab2+b3,它有四项,系数分别为1,3,3,1;

根据以上规律,(a+b)4展开式共有五项,系数分别为
1
4
6
4
1

计算:(a+b)4

查看答案和解析>>

阅读理解题:一次数学兴趣小组的活动课上,师生有下面一段对话,请你阅读完后再解答下面问题:
老师:同学们,今天我们来探索如下方程的解法:(x2-x)2-8(x2-x)+12=0.
学生甲:老师,先去括号,再合并同类项,行吗?
老师:这样,原方程可整理为x4-2x3-7x2+8x+12=0,次数变成了4次,用现有的知识无法解答.同学们再观察观察,看看这个方程有什么特点?
学生乙:我发现方程中x2-x是整体出现的,最好不要去括号!
老师:很好.如果我们把x2-x看成一个整体,用y来表示,那么原方程就变成y2-8y+12=0.
全体同学:咦,这不是我们学过的一元二次方程吗?
老师:大家真会观察和思考,太棒了!显然一元二次方程y2-8y+12=0的解是y1=6,y2=2,就有x2-x=6或x2-x=2.
学生丙:对啦,再解这两个方程,可得原方程的根x1=3,x2=-2,x3=2,x4=-1,嗬,有这么多根啊.
老师:同学们,通常我们把这种方法叫做换元法.在这里,使用它最大的妙处在于降低了原方程的次数,这是一种很重要的转化方法.
全体同学:OK!换元法真神奇!
现在,请你用换元法解下列分式方程

查看答案和解析>>

阅读下面一段材料,回答问题.
我国宋朝数学家杨辉在他的著作《详解九章算法》中提出下表,此表揭示了(a+b)n(n为非负整数)展开式的各项系数的规律,例如:
(a+b)0=1,它只有一项,系数为1;
(a+b)1=a+b,它有两项,系数分别为1,1;
(a+b)2=a2+2ab+b2,它有三项,系数分别为1,2,1;
(a+b)3=a3+3a2b+3ab2+b3,它有四项,系数分别为1,3,3,1;

根据以上规律,(a+b)4展开式共有五项,系数分别为_____
计算:(a+b)4

查看答案和解析>>

阅读理解题:一次数学兴趣小组的活动课上,师生有下面一段对话,请你阅读完后再解答下面问题:
老师:同学们,今天我们来探索如下方程的解法:(x2-x)2-8(x2-x)+12=0.
学生甲:老师,先去括号,再合并同类项,行吗?
老师:这样,原方程可整理为x4-2x3-7x2+8x+12=0,次数变成了4次,用现有的知识无法解答.同学们再观察观察,看看这个方程有什么特点?
学生乙:我发现方程中x2-x是整体出现的,最好不要去括号!
老师:很好.如果我们把x2-x看成一个整体,用y来表示,那么原方程就变成y2-8y+12=0.
全体同学:咦,这不是我们学过的一元二次方程吗?
老师:大家真会观察和思考,太棒了!显然一元二次方程y2-8y+12=0的解是y1=6,y2=2,就有x2-x=6或x2-x=2.
学生丙:对啦,再解这两个方程,可得原方程的根x1=3,x2=-2,x3=2,x4=-1,嗬,有这么多根啊.
老师:同学们,通常我们把这种方法叫做换元法.在这里,使用它最大的妙处在于降低了原方程的次数,这是一种很重要的转化方法.
全体同学:OK!换元法真神奇!
现在,请你用换元法解下列分式方程

查看答案和解析>>


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