化简求值:(1)求(a2+2ab+b2)―(a2―2ab+b2)的值.其中a=
,b=―1.
(2)求
(y2+4x)―(
x+
y2)―4(―
x+
y)的值.其中x=
,y=
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
更新时间:2016-12-05 22:33:38
|
【知识点】 整式的加减及运用
相似题推荐
解答题-问答题
|
适中
(0.65)
【推荐1】问题提出
我们在分析解决某些数学问题时,经常要比较两个数或代数式的大小,而解决问题的策略一般要进行一定的转化,其中“作差法”就是常用的方法之一.所谓“作差法”:就是通过作差、变形,并利用差的符号确定他们的大小.例如:
(1)对于任意两个代数式
的大小比较,有下面的方法:
当
时,
;
当
时,
;
当
时,
.
反过来也成立.因此,我们把这种比较两个代数式大小的方法叫做“作差法”.
(2)对于比较两个正数
的大小,我们还可以用它们的平方进行比较:
,
与
的符号相同.
当
时,
,得
;
当
时,
,得
;
当
时,
,得
.
问题解决
(3)课堂上,老师让同学们制作几种几何体,张丽同学用了3张
纸,7张
纸;李明同学用了2张
纸,8张
纸.设每张
纸的面积为
,每张
纸的面积为
,且
,张丽同学的用纸总面积为
,李明同学的用纸总面积为
.回答下列问题:
①
______(用含
的代数式表示);
______(用含
的代数式表示);
②试比较谁的用纸总面积更大?
(4)如图1所示,要在燃气管道
上修建一个泵站,向
两镇供气,已知
到
的距离分别是
(即
),
,现设计两种方案:
方案一:如图2所示,
于点
,泵站修建在点
处,该方案中管道长度
.
方案二:如图3所示,点
与点
关于
对称,
与
相交于点
,泵站修建在点
处,该方案中管道长度
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/22/fe1651e0-b0c2-4267-8808-83f70301f906.png?resizew=327)
①在方案一中,
______
(用含
的代数式表示);
②在方案二中,
______
(用含
的代数式表示);
③请分析说明哪种方案铺设的输气管道较短?
我们在分析解决某些数学问题时,经常要比较两个数或代数式的大小,而解决问题的策略一般要进行一定的转化,其中“作差法”就是常用的方法之一.所谓“作差法”:就是通过作差、变形,并利用差的符号确定他们的大小.例如:
(1)对于任意两个代数式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59edf1a399186f4a2b871f84eaa2ff7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f8f97cf2fc2d0676d6df01ff9759611.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63483f4bfef23358b59f859ce19d7de4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad96b50521f4bbf3d436d05dc258083d.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b56b39e28b89ed2744d8593a3828b269.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ba84caf91202df9aca6302e6860f82e.png)
反过来也成立.因此,我们把这种比较两个代数式大小的方法叫做“作差法”.
(2)对于比较两个正数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89f3a395c322a2a100d097dca7e84c3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/507bd85d7339022eb1548a5f98691097.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc239d331d0f3f91195a85eb9439dfb.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35112f17924afc79c0d0765ee518a0cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/481ee0d1e39e92a4732eea90225eb94c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/432d77fe5ad3032d59a237dd94c8a638.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3d08e682f2684d6f6c3816007f508c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/697c3d4b11fc2ae913cc27b6b63fc199.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f22fec5a381ae8aca93d876e54c79de.png)
当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4aa884853c2bb6762ad54d51cd1f8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4f7bea84b44a1dd19c1d3682688c7b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6a46e678bf9d2df5ad4c782b3dc22f5.png)
问题解决
(3)课堂上,老师让同学们制作几种几何体,张丽同学用了3张
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b553e2a281714677e29a5e97dd7d5a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ce9b2777caae9031fbbfc94ee268a2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b553e2a281714677e29a5e97dd7d5a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ce9b2777caae9031fbbfc94ee268a2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b553e2a281714677e29a5e97dd7d5a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ce9b2777caae9031fbbfc94ee268a2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b21208364124b5c477b2ff8df1c2e8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3dabace330ccdd9755fbcf32d5d6343.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b0fffbec1fe851795dfdd448bf0d165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1b625192d7398634a02ea24fa78ed87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b0fffbec1fe851795dfdd448bf0d165.png)
②试比较谁的用纸总面积更大?
(4)如图1所示,要在燃气管道
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89bebdc2222653da5a9ed32da5f5c484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56640fc672f452a833e70b9efde06b21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e22d7e4ed9a7103f8fd2e7ea6ae05ddd.png)
方案一:如图2所示,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/904b21bba351171abdc8482a906499d8.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/28461e0b8bf621aa1fa9bbf83fde5602.png)
方案二:如图3所示,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e663220a66eff19da6a71e46b397db2e.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/5028e85bfff95fb247ca70dc45d39c22.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/22/fe1651e0-b0c2-4267-8808-83f70301f906.png?resizew=327)
①在方案一中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7999465d0e871febde66296a0cbf058c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5fe30c67ac20cd4e8b9cc2d0d420a7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
②在方案二中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af9bbe98100c8067ff36ac536d043a85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5fe30c67ac20cd4e8b9cc2d0d420a7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
③请分析说明哪种方案铺设的输气管道较短?
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐2】如图:在数轴上点A表示数a,点B表示数b,点C表示数c,a是多项式
的一次项系数,b是最小的正整数,单项式
的次数为c.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/111eb8e8-5e3e-403c-b5f5-f82eec945bda.png?resizew=224)
(1)
______,
______,
______;
(2)若将数轴在点B处折叠,则点A与点C______重合(填“能”或“不能”);
(3)点A,B,C开始在数轴上运动,若点C以每秒1个单位长度的速度向右运动,同时,点A和点B分别以每秒3个单位长度和2个单位长度的速度向左运动,t秒钟过后,若点A与点B之间的距离表示为AB,点B与点C之间的距离表示为BC,则
______,
______(用含t的代数式表示);
(4)请问:
的值是否随着时间t的变化而改变?若变化,请说明理由;若不变,请求其值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed6e23819714c096e958bd2ddda12bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0736394991789bf9c238aad4f0af6948.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/111eb8e8-5e3e-403c-b5f5-f82eec945bda.png?resizew=224)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/380bbacf854e30e2e747fc286d2b9997.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4162c7d09f970cb77cadacdbe521.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4e9bb42376c12d7d21702ae8062b25a.png)
(2)若将数轴在点B处折叠,则点A与点C______重合(填“能”或“不能”);
(3)点A,B,C开始在数轴上运动,若点C以每秒1个单位长度的速度向右运动,同时,点A和点B分别以每秒3个单位长度和2个单位长度的速度向左运动,t秒钟过后,若点A与点B之间的距离表示为AB,点B与点C之间的距离表示为BC,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c26a46e7879436d532af3f4b6e258a81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16ca90e8a784f990c4097eec9219908d.png)
(4)请问:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f16954bad093253bf224cd6dba6ec49.png)
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