先化简,再求值:
,其中x满足条件
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad29b3112291012fbc2c5a8b500a5645.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5859d1931052df06b05ceac6112f4ac9.png)
更新时间:2020-10-23 07:03:49
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相似题推荐
解答题-计算题
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适中
(0.65)
【推荐2】先化简再求值:5(3a2b﹣ab2)﹣2(ab2+3a2b),其中a=﹣
,b=
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cfa1e7ffae662aefb49a44c52d4954d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dbad074ba78c0a942f9be7379aeff36.png)
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解答题-计算题
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适中
(0.65)
【推荐2】化简:
(1)﹣5a+(3a﹣2)﹣(3a﹣7)
(2)3(8xy﹣3x2)﹣5xy﹣2(3xy﹣2x2)
(1)﹣5a+(3a﹣2)﹣(3a﹣7)
(2)3(8xy﹣3x2)﹣5xy﹣2(3xy﹣2x2)
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解答题-计算题
|
适中
(0.65)
【推荐1】先化简,再求值:(3x+5)2﹣(2x﹣5)(2x+5)﹣5x(x+10),其中x=
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca83504e351d7516f61a3052d7a31859.png)
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解答题-计算题
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适中
(0.65)
【推荐2】计算:
(1)(π﹣3)0﹣
÷
+(﹣1)﹣1;
(2)
(1)(π﹣3)0﹣
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b4515f89a626f76189663da498cfa87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5466730b918f22d3898733ac10ebafbc.png)
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解答题-计算题
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适中
(0.65)
【推荐1】《见微知著》谈到:从一个简单的经典问题出发,从特殊到一般,由简单到复杂,从部分到整体,由低维到高维,知识与方法上的类比是探索发展的重要途径.恒等变形,是代数式求值的一个很重要的方法.利用恒等变形,可以把无理数运算转化为有理数运算,可以把次数较高的代数式转化为次数较低的代数式.
如:当
时,求
的值.若直接把
代入所求的式中,进行计算,显然很麻烦,我们可以通过恒等变形,对本题进行解答.
方法:将条件变形,因
,得
,再把等式两边同时平方,把无理数运算转化为有理数运算.
由
平方得
,整理可得:
,即
.
所以
.
请参照以上的解决问题的思路和方法,解决以下问题:
(1)若
,则
______,
______;
(2)若
,求
的值.
如:当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fbfafe2d43ef460f78bc91d322519ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01b05df4f34ee95f724ab14b417db116.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fbfafe2d43ef460f78bc91d322519ad.png)
方法:将条件变形,因
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fbfafe2d43ef460f78bc91d322519ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84168c800b2b77cda0287c53f85fac88.png)
由
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84168c800b2b77cda0287c53f85fac88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da87e6d0122b30a7f611816e44029f03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c222235ac990eb9249452c2606c1f86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f486752256a7b101d38742fca2ca656.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1482f3c1baa29a9f71c4f7b03f04b661.png)
请参照以上的解决问题的思路和方法,解决以下问题:
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74490a23cd584fd39cea93ca3ca07106.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a6bffa6b51a44ad24ab6e408f792565.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67f484b9da194af682044655f7c2fe97.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/753fac89b851c10a6db2979ec2606ec2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a47780c29b3b31a68f3b80a8c90a4516.png)
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解答题-问答题
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适中
(0.65)
【推荐2】阅读材料:若
,求m、n的值.
解:∵
,
∴
,
∴
,
∴
,
,
∴
,
.
根据你的观察,探究下面的问题:
(1)已知
,求
的值.
(2)已知
的三边长是a、b、c互不相等的正整数,且满足
.求
周长.(注:三角形任意两边之和大于第三边)
(3)已知
,
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19ab3cd8d4125c4ad18333dff0cce5f5.png)
解:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19ab3cd8d4125c4ad18333dff0cce5f5.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcf72e8aad5b0e809dc97ecb8d28a443.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8989fead62857fb90b5199bdcad51654.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8e59e8e73bff0cb4196b4e016d480d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98912998556ef3f2907bee2a7531dc50.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fac3649308b528fd56545ba102dc42d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/711b21672fd907c5c92fee1d649e7003.png)
根据你的观察,探究下面的问题:
(1)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2760622e5f5cedf5eab9bad41b80ecc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b116b1564318168685b534dfe321bfe.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d0045d331aa692e7ecea5f00dc1cb26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3691ffabdfd95805517d1e54ec8eec7c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/610762004b99cab80df3e56f12c8a4da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31ea3e6c83f28d4ff8edc2fd20152ba5.png)
您最近一年使用:0次