已知抛物线的解析式为y=﹣3x2+6x+9.
(1)求它的对称轴;
(2)求它与x轴,y轴的交点坐标.
(1)求它的对称轴;
(2)求它与x轴,y轴的交点坐标.
20-21九年级上·浙江绍兴·期中 查看更多[2]
更新时间:2020-12-27 23:12:07
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【推荐1】已知抛物线
与
轴交于点
、
(点
在点
的左侧),交
轴于点
.
(1)求点
、
、
的坐标;
(2)连接
,抛物线的对称轴
与
交于点
,对称轴
上是否存在点
,使得以点
、
、
为顶点的三角形与
相似,若存在,请求出点
的坐标;若不存在,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/117c9e031f8bc140d18f27963595729e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/29/58b85ed0-79bd-407a-aa37-caf42df76bba.png?resizew=133)
(1)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a7ffcd1925a2b1259221c6a476152f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
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名校
【推荐2】阅读材料:
材料:如图1,抛物线
的顶点为点D,对称轴交x轴于点E,点P为抛物线上任一点,过点P作对称轴的垂线,垂足为点N,若
,则
(俗称“海涛定理”).
证明:
,
,所以点P的横坐标为
,代入抛物线得点P的纵坐标为
,所以
,同理若
,
.
根据上述材料,结合你所学的知识,完成下列问题:
如图2,抛物线
的顶点为D,点A、B为抛物线上的点,连接
交抛物线的对称轴于点C,过点A、B作抛物线对称轴的垂线,垂足分别为H、K,若
,
,直接利用“海涛定理”求
的长.
材料:如图1,抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a90385c676848de67293e3ed6bc000fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d4e083291cb303ba74ab60a4f1d2408.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6788bc82bd9e0e199e3ab80ace93367.png)
证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c5bf910ef5170aebc53eabb554061bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d4e083291cb303ba74ab60a4f1d2408.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d436168d60581fc2d687204d8d293460.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36aa58aa0830c0111f9c3192ba7cb9e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c257b4df4b0a9de9cdbed13d51124449.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94440d3e4c073f94f2b266ff99d50e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ee84a7c1a1382b4f020998736943a42.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/11/4e2b5e2b-93fb-4549-b09e-3ec5112be1ff.png?resizew=257)
根据上述材料,结合你所学的知识,完成下列问题:
如图2,抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ba23d524dc2a51f2a2f5a2eec842f22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79a236e6039ccf4567769b06baa6137.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/947d3f1964822f0e1731d92e629becb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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【推荐1】已知二次函数
的图象如图所示,与坐标轴的交点分别为A、B、C.
(1)求此函数解析式,及A、B、C的坐标,
(2)如果点
是此二次函数的图象上一点,若
,则
的取值范围为______(直接写出结果)
(3)在
轴上方的抛物线上是否存在点D,使得
的面积为8,若存在,请求出点D的坐标;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4300f7330f90701510d019c9798fe49.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/8/d3a3ecd0-5787-4bdf-8166-77e0639100ff.png?resizew=431)
(1)求此函数解析式,及A、B、C的坐标,
(2)如果点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82aaa597a5aa6176863eda3fdf83e181.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db726b54384941dca3428e786b2a631f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
(3)在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
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【推荐2】已知二次函数y=x2﹣2(m+2)x+2(m﹣1)的图象的对称轴为直线x=4,判断该二次函数的图象与x轴是否有交点,并说明理由.
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【推荐1】已知抛物线
交
轴于点
,其对称轴在
轴右侧,点
在抛物线上,连接
D,
,且
轴.
(1)填空:点
的坐标为__________,对称轴是直线__________;
(2)求出
与
的关系式;
(3)若抛物线
与
轴交于
两点,且
,记抛物线
的顶点为
.现将该抛物线进行平移,使平移后的抛物线的顶点在直线
上运动,当平移后的抛物线经过点
时,求出平移后的抛物线的表达式.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3ff0ed1e582bc5af9577a38425ce060.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eca7e1a727ba332984ad857b3d25344d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4d6eb67e32034c7c7312d6442e5ef40.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/26/5d00dcd7-d316-4438-8e62-8ff503bf6c63.png?resizew=236)
(1)填空:点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
(2)求出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
(3)若抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b4a57fa701747e4b70ce26eb18ab8cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/482cb961a768bd9d64e5284772aec8da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f0e65e147b109f2bbfd3a3f502bbc3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf5f0df2579e567038baa206cb0b016f.png)
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【推荐2】在平面直角坐标系中,点
,
在抛物线
上.
(1)写出该抛物线与y轴的交点坐标;
(2)已知
.
①求a,b满足的数量关系;
②已知点
在该抛物线上,当
时,求y的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5bac94908f9f24ef1618a72cece5cba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87a11362ec4cce9314a4558365ca4404.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8dd4534f6b65873203976e56d84e5b9.png)
(1)写出该抛物线与y轴的交点坐标;
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0a4480988244a9d04ec293975db2cc0.png)
①求a,b满足的数量关系;
②已知点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a77b96fc51eb8a9d03ced254ce8b78be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2da45e190edb2230c9b6495647954d1c.png)
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