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【331085】6.2 反比例函数的图象与性质(第1课时)

时间:2025-01-21 13:37:03 作者: 字数:2990字
简介:









6.2反比例函数的图象与性质(第1课时)

  1. 问题引入

1、画函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象: <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>

2、我们已知道,一次函数y=kx+bk≠0)的图象是一条直线,那么反比例函数 (k为常数且k≠0)的图象是什么样呢?

二、基础训练:

画出反比例函数y= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> y=- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象.

解:列表

x

-6

-5

-4

-3

-2

-1

1

2

3

4

5

6

y= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>



-1


-1.5

-2


-6


3



1


y=- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>


1

1.2



3

6




-1.5




描点,以表中各对应值为坐标,在直角坐标系中描出各点.

连线,用平滑的曲线把所描的点依次连接起来.

组合 1634 组合 611












探究:反比例函数y= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> y=- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象有什么共同特征?它们之间有什么关系?

y= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> y=- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象放到同一坐标系中,观察一下,看它们是否对称.

归纳:反比例函数y= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> y=- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象的共同特征:

1____________________ 2________________________________________

三、例题展示

1、反比例函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象分布在二、四象限,求k的取值范围





2已知反比例函数y = (k < 0)的图象上有两点A (x1y1)B (x2y2),且x1 < x2试比较y1y2大小.





3、如图所示,已知直线y1=x+mx轴、y轴分别交于点AB,与双曲线y2= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> k<0)分别交于点CD,且C点坐标为(-12).

1)分别求直线AB与双曲线的解析式;

2)求D的坐标;

3)利用图象直接写出当x在什么范围内取何值时,y1>y2

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>

  1. 课堂检测:

  1. .已知m<-1,则下列函数:① y = (x>0),② y = -mx +1;③y = (m +1)x;④ y = - (x<0)中,yx的减小而增大的是 (填入函数代号).

  2.  <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 0, <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 0时,反比例函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象在(

A.第一象限 B.第二象限 C.第三象限 D.第四象限

3、若反比例函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图象位于第二、四象限,则 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的值是(

A. 0 B. 01 C. 02 D. 4

4、当k>0时,下列图象中哪个可能是y=kxy= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> k≠0)在同一坐标系中的图象 ( )

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>

5、已知一次函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图像与反比例函数 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a> 的图像交于AB两点,且点A的横坐标和点B的纵坐标都是-2

求(1)一次函数的解析式;

2)△AOB的面积.

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/386/" title="性质" class="c1" target="_blank">性质</a> <a href="/tags/411/" title="反比例" class="c1" target="_blank">反比例</a> <a href="/tags/885/" title="函数" class="c1" target="_blank">函数</a> <a href="/tags/898/" title="图象" class="c1" target="_blank">图象</a>