已知函数y=ax2﹣2x+2,对满足3<x<4的任意x都有y>0成立,实数a的取值范围是( )
A.a>0 | B.![]() ![]() | C.![]() ![]() | D.a>![]() |
更新时间:2019-01-20 22:53:57
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【知识点】 根据二次函数的图象判断式子符号解读
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【推荐1】二次函数
的图象如图所示,下列结论:①
;②
;③m为任意实数,则
;④
;⑤若
且
,则
.其中正确的有( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe6337d68cd5653767e3a1889b8b2e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73c21bd0bd90a89b7ff5ac0eacf612a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa285de4d015f208441ffe9a84bbd780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c024a97cff31cb54b6026300808798.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da68ff94b0877adb96abbc3e0fa52d86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e742f40beb84937aa8d49ae52416a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33bd24e647a626899a243a3f3984f90a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/419504736c4934f6e0df4114c3743944.png)
A.①④ | B.③④ | C.②⑤ | D.②③⑤ |
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【推荐2】如图,抛物线y=ax2+bx+c(a≠0)的对称轴为直线x=1,与x轴的一个交点坐标为
,其部分图象如图所示,下列结论:①
;②方程ax2+bx+c=0的两个根是
,x2=3;③3a+c>0;④当y>0时,x的取值范围是
;⑤当x<0时,y随x增大而增大,其中结论正确的个数是( )
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/9/446de04b-17f8-4613-99d2-397b07dc8940.png?resizew=156)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc6554ac3dff4a59833e407db887f6e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4630bb948780be53bc73d9ddef875000.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4049b329e8cf711663e050e0dc9cdea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b16589640a4b86c5c10620b267884982.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/9/446de04b-17f8-4613-99d2-397b07dc8940.png?resizew=156)
A.4个 | B.3个 | C.2个 | D.5个 |
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