已知
,
,且a<b,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/470a1794cff2b48447e79d1f85c603db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7f21978703ce7ea68c7b4d300770d7c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96f618a5a13134ac4775c494d351afc4.png)
更新时间:2018-11-24 09:01:02
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相似题推荐
解答题-问答题
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【推荐1】综合与实践:
【问题情景】我们知道,有理数x的绝对值有如下结论:
,现在我们用这一个结论去探究含有绝对值代数式的化简方法与过程.
【实践发现】以化简代数式
为例,我们可令
和
, 分别求得
,
(这里,我们称
,2分别为
与
的零点值).在有理数范围内,零点值
和
可将全体有理数范围分成不重复且不遗漏的3种情况:①
,②
,③
.接下来就可分情况来完成化简了.解题过程如下:
解:令
和
,分别求得
,
.
①当
时,原式
;
②当
时,原式
;
③当
时,原式
.
综上讨论,原式
.
【问题解决】通过以上探究,解决以下问题:
(1)求出
和
的零点值;
(2)化简代数式
.
【问题情景】我们知道,有理数x的绝对值有如下结论:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7092fd81e85e03522334ec102267503f.png)
【实践发现】以化简代数式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40cfb936d8d761ccbe51b7892bd898a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/122fa7155f6858a570e8dee2495822a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9378f4030a56301dfdf892c0b36182b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef00713e73b8357cc7900144f5505bc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acbc6a613224461ade69362d46550474.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9b90f5a50cabc6cad1b36bf25fc6d37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70b4feb90b84eb54fe644c596f5156a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef00713e73b8357cc7900144f5505bc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7da6d82d173ad18cc040e94c925b5ab9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/964fd15ed03eefd8a51b29e9e99deaf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b27f27cbb8185c1974d715ff95f8801c.png)
解:令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/122fa7155f6858a570e8dee2495822a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9378f4030a56301dfdf892c0b36182b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef00713e73b8357cc7900144f5505bc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7da6d82d173ad18cc040e94c925b5ab9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04d9fc52b1716c3f52c8da26734910d4.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/964fd15ed03eefd8a51b29e9e99deaf5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3699f4bc5f414a4c831f18ded6d3c30.png)
③当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b27f27cbb8185c1974d715ff95f8801c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3514a90dcbd80ddddd127c877750cd1.png)
综上讨论,原式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d88f08bd4a5385f475005f3aea2cf0c.png)
【问题解决】通过以上探究,解决以下问题:
(1)求出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fe56a82278b144101fda1fa2cf59703.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33931651893cffc7112c99e608333059.png)
(2)化简代数式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b0a02595228c8884f2090ba5a22df58.png)
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【推荐2】同学们都知道,
表示5与
之差的绝对值,实际上也可理解为5与
两数在数轴上所对应的两点之间的距离,试探索:
(1)求
= .
(2)若
,则
=
(3)同理
表示数轴上有理数x所对应的点到
和2所对应的两点距离之和,请你找出所有符合条件的整数x,使得
,这样的整数是 (直接写答案)
(4)用上面学到的知识回答满足
的x的值为 .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea7ba690de4bdbdceb968265181a208f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274a9dc37509f01c2606fb3086a46f4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274a9dc37509f01c2606fb3086a46f4f.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea7ba690de4bdbdceb968265181a208f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/896ab4ba36a472b8e76da406ed504aca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(3)同理
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/479e6df4ec81331c3e00ef341ccff745.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acbc6a613224461ade69362d46550474.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f169e2290e971101216b41642913241.png)
(4)用上面学到的知识回答满足
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/617aaad1fac4a6b2532c59c8c6e8d218.png)
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【推荐1】某厂现有
种原料
,
种原料
,现计划用这两种原料生产
,
两个品种的饮料,已知生产每千克
品种的饮料需要
种原料
,
种原料
,可获利
元,生产每千克
品种的饮料只需要
种原料
,可获利3千元,两种原料正好用完.
(1)生产
品种的饮料________千克.
(2)生产
品种的饮料使用
种原料多少千克?
(3)该厂共获利多少元?(用含
,
的式子表示)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b51a293b9810a569e5240db168296044.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57714942d1b235ccb7013357a0b8cc92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0febd1d4d5b33a7e94868cf587b795d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f93034eaf5a7102d6db7218551a28a68.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e85aa22b8f2ff1565d2b386dbe5a9b9b.png)
(1)生产
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
(2)生产
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
(3)该厂共获利多少元?(用含
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
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【推荐2】一辆出租车从A地出发,在一条东西走向的街道上往返,每次行驶的路程(向东记为正,向西记为负)记录如下:(
,单位:
)
(1)写出这辆出租车每次行驶的方向:第一次向东,第二次向西,第三次向______,第四次向______;
(2)若
,求经过连续4次行驶后,这辆出租车在A地的什么方向,距离A地有多远?
(3)求这辆出租车4次行驶的总路程(结果用含x的式子表示).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/844ddcb814bea88fa3d342a4c34e4346.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5fe30c67ac20cd4e8b9cc2d0d420a7b.png)
第一次 | 第二次 | 第三次 | 第四次 |
x | ![]() | ![]() | ![]() |
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34a6f3846904b1a225ee1d3d7d491cbb.png)
(3)求这辆出租车4次行驶的总路程(结果用含x的式子表示).
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