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http://www.pep.com.cn/czsx/jszx/jszj/gzsxgrzjjs_1/czsxqzh/qinzuhai7s/201303/t20130308_1150763.htm

中考演练

以下资源均来自于：http://www.jyeoo.com/math/ques/search?f=1&s=1&t=0&q=42

一、单项式

二、多项式

原文：

Tony: Mmm ... That smells delicious! What are you making? 
Betty: Hi, guys! I've made a pizza. Have some! 
Tony: OK. Yes, it's great. 
Betty: What's the matter, Daming? 
Daming: It tastes too strong. I'm afraid I don't like cheese. It doesn't smell fresh. No, thanks. 
Lingling: Well, I've made some chocolate cookies. Have a try! They taste really sweet.
Daming: That's much better. 
Betty: You're wearing a lovely sweater, Lingling.
Lingling: Yes, it feels very soft and comfortable. 
Tony: You both look very smart. And so much food! Are we having a party? 
Lingling: We're going to the airport to meet my friend Sally from London.
Daming: What's she like? 
Lingling: I haven't met her, but she sounds really nice. 
Betty: And she looks very pretty in her photo. 
Tony: Let's have a look. Hm, yes, I see what you mean! 
Lingling: And then we're coming back here to have something to eat. 
Tony: You must introduce me to her. 
Betty: Sure we will. We'll be back soon. 
Lingling: See you later.

一.重点知识

1.一元一次方程ax+b=0(a≠0)与一次函数y=ax+b(a≠0)的关系
　　(1)一元一次方程ax+b=0(a≠0)是一次函数y=ax+b(a≠0)的函数值为0时的特殊情形。
　　(2)直线y=ax+b与x轴交点的横坐标是一元一次方程a+b=0的解

 
2.一元一次不等式与一次函数的关系：
　　 (1)一元一次不等式ax+b>0或ax+b<0(a≠0)是一次函数y=ax+b (a≠0)的函数值不等于0的情形。
　　 (2)直线y=ax+b上使函数值y>0(x轴上方的图像)的x的取值范围是ax+b>0的解集；使函数值y<0(x轴下方的图像)的x的取值范围是ax+b<0的解集。
3.二元一次方程与一次函数的联系
　　 (1)任意一个二元一次方程都可化成y=kx+b的形式，即使每个二元一次方程都对应一个一次函数，也对应一条直线。
　　 (2)直线y=kx+b的每一点的坐标均为这个二元一次方程的解。
4.二元一次方程组与一次函数的关系
　　 (1)二元一次方程组中的每个方程可看作函数解析式。
　　 (2)求二元一次方程组的解可以看作求两个一次函数的交点坐标。

二.方法技巧
1.利用一次函数求一元一次方程的解题步骤。
　　(1)将一元一次方程化成ax+b=0的形式
　　(2)画出y=ax+b的图像，确定其与x轴交点的横坐标。
2.利用一次函数式求一元一次不等式的解集的技巧
　　根据不等式的特点，灵活采用求解方程： (1)利用一个一次函数；(2)利用两个一次函数。
3.利用一次函数解二元一次方程组的步骤
　　(1)将方程组中的每个方程转化成一次函数y=kx+b的形式。
　　(2)在同一直角坐标系中画出两函数的图像。
　　(3)利用图像的直观性确定交点坐标。
4.求两个一次函数的交点坐标的方法
　　 解由两个一次函数的解析式组成的二元一次方程组，就能准确地求出交点坐标。 
5.两个一次函数图像交点的作用
　　 借助图像的直观性，利用交点坐标，可以解决有关比较，决策等生活实际问题。

做一做：

1、指出函数y=3x-6的自变量与因变量，并作出其图象，用图象法求出当x取何值时，

（1）3x-6＞0 （2）3x-6＜0

2、用直接解不等式的方法求上题中的有两个不等式的解集，并比较两种方法的结果相同吗？

3、作出函数y=2x-5的图象，观察图象回答下列问题：

（1）x取哪些值时，2x-5＞0？

（2）x取哪些值时，2x-5＜0？

（3）x取哪些值时，2x-5＞3？

原文：

Tony: Mmm ... That smells delicious! What are you making? 
Betty: Hi, guys! I've made a pizza. Have some! 
Tony: OK. Yes, it's great. 
Betty: What's the matter, Daming? 
Daming: It tastes too strong. I'm afraid I don't like cheese. It doesn't smell fresh. No, thanks. 
Lingling: Well, I've made some chocolate cookies. Have a try! They taste really sweet.
Daming: That's much better. 
Betty: You're wearing a lovely sweater, Lingling.
Lingling: Yes, it feels very soft and comfortable. 
Tony: You both look very smart. And so much food! Are we having a party? 
Lingling: We're going to the airport to meet my friend Sally from London.
Daming: What's she like? 
Lingling: I haven't met her, but she sounds really nice. 
Betty: And she looks very pretty in her photo. 
Tony: Let's have a look. Hm, yes, I see what you mean! 
Lingling: And then we're coming back here to have something to eat. 
Tony: You must introduce me to her. 
Betty: Sure we will. We'll be back soon. 
Lingling: See you later.

1、兄弟俩赛跑，哥哥先让弟弟9m，然后自己才开始跑，已知弟弟每秒跑3m，哥哥每秒4m，列出函数关系式，画出函数图象，观察图象回答下列问题：

（1）何时弟弟跑在哥哥前面？

（2）何时哥哥跑在弟弟前面？

（3）谁先跑过20m？谁先跑过100m？

（4）你是怎样求解的？与同伴交流。

2、若y1=-x+3,y2=3x-4,试确定当x取何值时

（1）y1＜y2？

（2）y1=y2？

（3）y1>y2？

3、甲、乙两辆摩托车从相距20km的A、B两地相向而行，图中l1、l2分别表示两辆摩托车离开A地的距离s（km）与行驶时间t（h）之间函数关系。

（1）哪辆摩托车的速度较快？

（2）经过多长时间，甲车行驶到A、B两地中点？

原文提示：

Tony: Mmm ... That smells delicious! What are you making? 
Betty: Hi, guys! I've made a pizza. Have some! 
Tony: OK. Yes, it's great. 
Betty: What's the matter, Daming? 
Daming: It tastes too strong. I'm afraid I don't like cheese. It doesn't smell fresh. No, thanks. 
Lingling: Well, I've made some chocolate cookies. Have a try! They taste really sweet.
Daming: That's much better. 
Betty: You're wearing a lovely sweater, Lingling.
Lingling: Yes, it feels very soft and comfortable. 
Tony: You both look very smart. And so much food! Are we having a party? 
Lingling: We're going to the airport to meet my friend Sally from London.
Daming: What's she like? 
Lingling: I haven't met her, but she sounds really nice. 
Betty: And she looks very pretty in her photo. 
Tony: Let's have a look. Hm, yes, I see what you mean! 
Lingling: And then we're coming back here to have something to eat. 
Tony: You must introduce me to her. 
Betty: Sure we will. We'll be back soon. 
Lingling: See you later.