已知a2+b2+2a-4b+5=0,求2a2+4b-3的值.
更新时间:2017-12-23 20:48:19
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【知识点】 通过对完全平方公式变形求值解读
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解答题-问答题
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适中
(0.65)
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【推荐1】已知:
,
.
求:(1)
的值; (2)
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eaae3641ea4eacb9d7cf153117f74b0a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fa22b44f970e8f88eadfed48974d64f.png)
求:(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1e9bcf43dfc473bdbbc0624985f7e44.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc5f85f56005d1828a804d397e129db.png)
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解答题-问答题
|
适中
(0.65)
【推荐2】将两数和(差)的平方公式:
,通过适当的变形,可以解决很多数学问题.
例如:若
,
,求
的值.
解:
,
,
.
请根据上面的解题思路和方法,解决下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/b23b47f9-111d-4bc7-b104-0f96b37c462c.png?resizew=360)
(1)若
,
,求
的值;
(2)将边长为x的正方形
和边长为y的正方形
按如图所示放置,其中点D在边
上,连接
,
,若
,
,求阴影部分的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99e97c13d73ba9243e931e8dba7d9243.png)
例如:若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69fa88c6067600f8f279243972cd791b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca27cc54ca0332245f5167488daa3408.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c925be255ca736a53b24d13ddede1a86.png)
解:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0856962305f26b21308c01fd7bf1758c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca27cc54ca0332245f5167488daa3408.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64333e795ce836f2673d637fdaeaf4aa.png)
请根据上面的解题思路和方法,解决下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/b23b47f9-111d-4bc7-b104-0f96b37c462c.png?resizew=360)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83366dc77692c105cdfc99b028b18dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b0b28cd195507b17303c65f44588605.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f29d5f376c75c41ae6af0c8a8565449.png)
(2)将边长为x的正方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b1f13007c6d134c50004c62dc240707.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e55e398e8520d8a36fb5a625a085b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31b9442c77f394e24f722e626d85d249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f24a5cdab602a341d50e995ded7b873.png)
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