已知二次函数 y=ax2+bx+c,其中 y 与 x 的部分对应值如表:
下列结论正确的是( )
x | -2 | -1 | 0.5 | 1.5 |
y | 5 | 0 | -3.75 | -3.75 |
下列结论正确的是( )
A.abc<0 | B.4a+2b+c>0 |
C.若 x<-1 或 x>3 时,y>0 | D.方程 ax2+bx+c=5 的解为 x1=-2,x2=3 |
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更新时间:2020-07-06 20:41:18
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【推荐1】定义:在平面直角坐标系
中,函数图象上到一条坐标轴的距离等于
,到另一条坐标轴的距离不大于
的点叫做该函数图象的“
方内点”.
对于下列四个结论:
①点
是一次函数
图象的“2方内点”;
②函数
图象上不存在“2方内点”;
③若直线
的“
方内点”有两个,则
;
④当函数
的“
方内点”恰有3个时,符合条件的
的值也有3个.其中正确的序号为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f2beb91f10d2d8f2aa0dcc3f5cd1598.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
对于下列四个结论:
①点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25f114df5ceabdb7e5fd3fdad4eaf056.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08b9f0b9e53a83e68f5fec944f343119.png)
②函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8684443809254c64330bb349b473bda5.png)
③若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/17be549af41c73cdf6be85d63884d475.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f421794ba6a39794fe94c55117112a4.png)
④当函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2f0523bf8bbe538f51e70ae3243443d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
A.①②③ | B.①②③ | C.①③④ | D.②③④ |
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【推荐2】关于
的二次函数
.下列说法:①无论
取何值,此二次函数图象与
必有两个交点;②无论
取何值,图象必过两定点,且两定点之间的距离为
;③当
时,函数在
时,
随
的增大而减小;④当
时,函数图象截
轴所得的线段长度必大于2,其中结论正确的个数有 ( )
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【推荐1】二次函数y=ax2+bx+c的图象如图所示,以下结论:①abc>0;②4ac<b2;③2a+b>0;④其顶点坐标为(
,﹣2);⑤当x<
时,y随x的增大而减小;⑥a+b+c>0,正确的有( )
![](https://img.xkw.com/dksih/QBM/2017/12/31/1850197845090304/1853974807199744/STEM/263d701cab514245933ff05d776c4b6b.png?resizew=137)
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A.3个 | B.4个 | C.5个 | D.6个 |
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【推荐2】如图,抛物线
的顶点和抛物线与
轴的交点在一次函数
的图象上,它的对称轴是
,有下列四个结论:①
;②
;③当
时,
.其中正确结论的个数是( )
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【推荐1】已知二次函数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a90385c676848de67293e3ed6bc000fe.png)
的图象如图所示,以下结论:①
;②
;③
;④
;⑤若此函数的最大值为
,二次函数
的最大值为
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【推荐2】如图是抛物线
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