如图,抛物线y=ax2+bx﹣4(a≠0)与x轴交于A(2,0)、B(﹣4,0)两点,与y轴交于点C,矩形DEFG的一条边DE在线段AB上,顶点F,G分别在线段BC、AC上.
(I)求抛物线的解析式;
(II)若点D的坐标为(m,0),矩形DEFG的面积为S,求S与m的函数关系式,并指出m的取值范围;
(III)当矩形DEFG的面积S取最大值时,连接DF并延长至点M,使FM=k•DF.若点M在抛物线上,求k的值.
(I)求抛物线的解析式;
(II)若点D的坐标为(m,0),矩形DEFG的面积为S,求S与m的函数关系式,并指出m的取值范围;
(III)当矩形DEFG的面积S取最大值时,连接DF并延长至点M,使FM=k•DF.若点M在抛物线上,求k的值.
![](https://img.xkw.com/dksih/QBM/2018/11/27/2084781251690496/2085132985720832/STEM/c766da591d2744baa96c587a91c47cea.png?resizew=151)
更新时间:2018-11-28 09:16:49
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【知识点】 面积问题(二次函数综合)
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【推荐1】如图1,抛物线
经过点
、
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上一动点(不与点B重合),连接
,
,
,将
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,
交抛物线的另一点为Q,连接
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![](https://img.xkw.com/dksih/QBM/2021/5/10/2718154817937408/2726366786396160/STEM/fa580009-d789-451c-a915-dadb10c43d2f.png?resizew=482)
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①求点Q的坐标.
②若
的面积为
面积的8倍,请直接写出点N的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b286a72a818ccc52e63581841da08dd7.png)
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(3)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32e795fada08b9ca992db3f21cf63653.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3171b3d11c6f4619e189677345357508.png)
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解答题-证明题
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困难
(0.15)
【推荐2】如图,抛物线y=x2﹣(m+2)x+3(m﹣1)与x轴的两个交点为A、B,与y轴交于点C,点D为抛物线的顶点,直线y=﹣2x+m+6经过点B,交y轴于点E(0,6).
(1)求直线和抛物线的解析式;
(2)如果抛物线的对称轴与线段BC交于点H,且直线y=x与直线y=﹣2x+m+6交于点G,求证:四边形OHBG是平行四边形;
(3)在抛物线上是否存在点P,使△APB的面积等于平行四边形OHBG的面积,若存在,直接写出P点的坐标,若不存在请说明理由.
(1)求直线和抛物线的解析式;
(2)如果抛物线的对称轴与线段BC交于点H,且直线y=x与直线y=﹣2x+m+6交于点G,求证:四边形OHBG是平行四边形;
(3)在抛物线上是否存在点P,使△APB的面积等于平行四边形OHBG的面积,若存在,直接写出P点的坐标,若不存在请说明理由.
![](https://img.xkw.com/dksih/QBM/2017/8/28/1761750671130624/1761789945315328/STEM/b0d52772f0ec456c9325d7a57bc840a3.png?resizew=174)
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