请阅读下列解方程
的过程.
解:设
,则原方程可变形为
,即
,得
,
.
当
,
,∴
,
,当
,
,无解.
所以,原方程的解为
,
.
这种解方程的方法叫做换元法.
用上述方法解下面两个方程:
(1)
;
(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2803dd4829892261c94d222356a8d24.png)
解:设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c6301b9eaa38e1d1e576868a8fdb9ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ce763e15340572cf81ca423d5c27731.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba3c3c5af207b54d4d51b7674d0cc413.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebabdf565f48b49fe2ccd2486498a7fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b855fdb6b4dcbb080737a2dd26703897.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66884efff7400f92b530d69d029778d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40b5bd7473999e426415ab37659273a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fba0f69d58014f6ecf09a602976e468.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be1d26787e79bcd89c9338528308650b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1d86b4ad722d7b720603eba9d330fd1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51a11c538a2fdc64c1f118d3d0d7261b.png)
所以,原方程的解为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fba0f69d58014f6ecf09a602976e468.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be1d26787e79bcd89c9338528308650b.png)
这种解方程的方法叫做换元法.
用上述方法解下面两个方程:
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2c607c4682ae26f99f4f735f6eb2075.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8365d65fa051a16da0c24f2c9ee558c8.png)
22-23九年级上·广东江门·期中 查看更多[4]
广东省江门市新会葵城中学2022-2023学年九年级上学期期中考试数学试卷(已下线)专题2.15 换元法解一元二次方程(知识讲解)-2022-2023学年八年级数学下册基础知识专项讲练(浙教版)(已下线)专题17.15 换元法解一元二次方程(知识讲解)-2022-2023学年八年级数学下册基础知识专项讲练(沪科版)广东省韶关市新丰县2023-2024学年九年级上学期期中数学试题
更新时间:2022-12-08 09:48:42
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解答题-问答题
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适中
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【推荐2】如图,抛物线y=
+bx+c经过坐标原点,并与x轴交于点A(2,0).
![](https://img.xkw.com/dksih/QBM/2022/1/9/2890544298098688/2890748696805376/STEM/c819b0ac-c566-4bca-a215-d4fd0ea70b8c.png?resizew=204)
(1)求此抛物线的解析式;
(2)写出顶点坐标及对称轴;
(3)若抛物线上有一点B,且
=8,求点B的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/155dc53ae86a320c3ef6e531899795b6.png)
![](https://img.xkw.com/dksih/QBM/2022/1/9/2890544298098688/2890748696805376/STEM/c819b0ac-c566-4bca-a215-d4fd0ea70b8c.png?resizew=204)
(1)求此抛物线的解析式;
(2)写出顶点坐标及对称轴;
(3)若抛物线上有一点B,且
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解答题-问答题
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适中
(0.65)
【推荐1】阅读下面的材料:
为解方程
,我们可以将
视为一个整体,然后可设
,则
,原方程可化为
,解得
,
.
当
时,
,
,
;
当
时,
,
,
.
综上所述,原方程的解为
,
,
,
.
(1)根据材料解方程:
;
(2)已知实数
,
满足
,求
的值.
为解方程
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac22e4c7b6910d461fe874a4825af1a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4e1fbe0fb49725cf6d1e689ee8986d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8da7c06be71acd821a73fadba4d1c35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cf83a1e1a93986c879bdf9052b162ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d508887ede441f4d498565ceeb8682a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cda6ab0f37a6a39baffa6c98dc11dc16.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aeb68f02e333c48c66a2656d5115cf46.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c50866229ec5a3640fb250f9bd2192b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fbce8eb03871d4563436ddd3c2eb1808.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/204e5160ff110a19878e4fae639319e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b126fc0823afa6deefc8df35666c7800.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de72a5190834f5dbe895596656c038b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35f227df33998c627b586997a32d8f62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b7ec01c5228e1cf9df7c2aab8775f50.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/231e1417338a801f409486f29431d918.png)
综上所述,原方程的解为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e370d4caeeab628e65b82b0104114aad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8e9eb18f22ed5b7927a0d0bfa988bb0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42cb565d4ee7a36e30865423e8524558.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f3a4f822af22da2612d0ce447dc2ce.png)
(1)根据材料解方程:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33645016ba7d1738d85aa0afed0d049f.png)
(2)已知实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d086058b700e8528b49c13f060c98795.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/391a4a71bc4f4439a1437dce3f86a803.png)
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