题目内容
已知
,
与
+1成正比例,
与
+1成反比例,当
=0时,
=-5;当
=2时,
=-7。求
与
的函数关系式
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854156520.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854171333.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854187271.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854203374.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854187271.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854187271.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854234313.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854187271.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854234313.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854234313.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854187271.png)
y=-2(x+1)-![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854312392.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854312392.png)
)∵
与x+1成正比例,
与x+1成反比例,
∴可设
=
(x+1),
=
,
∴y=
+
=
(x+1)+
,
∵当x=0时y=-5,x=2时y=-7,
∴![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854468918.png)
解得
=-2,
=-3,
∴y关于x的函数关系式为:y=-2(x+1)-![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854312392.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854327320.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854343347.png)
∴可设
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854327320.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854374322.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854343347.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854390429.png)
∴y=
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854327320.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854343347.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854374322.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854390429.png)
∵当x=0时y=-5,x=2时y=-7,
∴
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854468918.png)
解得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854374322.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854499343.png)
∴y关于x的函数关系式为:y=-2(x+1)-
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823012854312392.png)
![](http://thumb.zyjl.cn/images/loading.gif)
练习册系列答案
相关题目