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1、名师精编优秀教案第十九章一次函数19.2 一次函数19.2.1正比例函数（2）【教学目标】知识与技能能根据正比例函数的图像，观察归纳出函数的性质；并会简单应用。过程与方法逐步培养学生的观察能力，概括的能力。情感、态度与价值观通过教师指导发现知识，初步培养学生数形结合的思想以及由一般到特殊的数学思想。【教学重难点】重点：正比例函数的性质及其应用。难点：发现正比例函数的性质【导学过程】【知识回顾】描点法画函数图象的一般步骤是：、【新知探究】探究一、在两个直角坐标系内，分别画出下列每组函数的图像：y=2x y=31x y=4x y=1.5x 引导学生观察图像，看看每组直线分布的特征？观察图像，思考问
2、题：图像经过的象限与k 的取值有何联系？不够明确。图像经过的象限与k 的取值（特别是符号）有何联系？对其中的某一个正比例函数图像(例如y=2x)，当 x 增大时，函数值y怎 样 变 化？x减小呢？是不是要提出减小？你从中得出什么规律？通过观察两图象可发现如下规律，你能将此规律补充完整吗？两图象都是经过点的线，函数y=2x 的图象经过第象限，从左向右呈趋势即 y 随着x 的增大而，函数y=-2x的图象经过第象限从左向右呈趋势，即y 随着 x 的增大而。4 4 3 3 2 2 1 1-1-1-2-2-3-3-4-4 O Y X 名师精编优秀教案探究二、这种规律对其他正比例函数适用吗？具有一般性吗？
3、请同学们在同一坐标系内画出1y2x、1y2x进行验证。总结、一般地正比例函数的y=kx（k 是常数，k0）的图象是一条经过的直线，我们称它为直线y=kx当 k0 时，直线y=kx 经过第象限，从左向右上升，即随着 x 的增大反而；当 k0（提）k0（提）k0（捺）正比例函数y=kx(k 0)是 经 过 原 点（0,0）和（1，k）的一条直线。一、三象限 二、四象限y 随着的x 增大而增大y 随着 x 的增大而减小【随堂练习】1、正比例函数的解析式是，它的图像一定经过。2、y=2x的图像经过第象限。3、已知 ab 0，则函数y=ab x 的图象经过象限。4、已知正比例函数y=(2a+1)x，若
4、y 的值随 x 的增大而减小，求a 的取值范围。5、当 m为何值时，y=mxm2-3是正比例函数，且y 随 x 的增大而增大。正比例函数的解析式具有共同的结构，那么他们的图像是否也具有某种必然的共同之处呢？6、用你认为最简单的方法画出下列正比例函数的图象：(1)y=3x (2)y=-5x 文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD
5、6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码
6、:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7
7、 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4
8、ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档
9、编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8
10、Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D
11、4 ZD6N1W4A1T8名师精编优秀教案【例 3】根据下列条件求函数的解析式y 与 x2成正 比例，且x=-2 时 y=12函数 y=（k2-4）x2+（k+1）x 是正比例函数，且y 随 x 的增大而减小 2正比例函数的性质（由学生归纳）六、布置作业，专题突破（课本 P120习题 142 第 1、2、3 题）课时作业1形如 _的函数是正比例函数2正比例函数y=kx，（1）若比例系数为-13，则函数关系式为_ ；（2）?若点经过（5，-1），则函数关系式_ 3、（1）已知函数y=（m-2）xm-1，m_时，y 是 x 的正比例函数；（2）若 x、y 是变量，且函数y=（k+1）xk是正比例函
12、数，则k=_4正比例函数y=kx（k 为常数，kx2，则 y1与 y2?的大小关系是（）Ay1y2 By1y2 Cy1=y2 D以上都有可能9写出下列各题中x 与 y 的关系式，并判断y 是否是 x 的正比例函数？（1）电报收费标准是每个字0.1 元，电报费y（元）与字数x（个）之间的函数关系；（2）地面气温是28，如果每升高1km，气温下降5，则气温x（?）?与高度 y（km）的关系；（3）圆面积y（cm2）与半径x（cm）的关系文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8
13、文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10
14、G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R
15、5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1
16、T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B
17、10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W
18、9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4
19、A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8名师精编优秀教案7C 学科网，最大最全的中小学教育资源网站，教学资料详细分类下载！文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S
20、7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y
21、4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1
22、W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ
23、8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG
24、1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8文档编码:CZ8S7B10G8Y7 HG1Y4W9R5D4 ZD6N1W4A1T8