运算律是解决许多数学问题的基础,在运算中有重要的作用,充分运用运算律能使计算简便高效.
例如:(-125
)÷(-5)
解:(-125
)÷(-5)=125
×
=(125+
)×
=125×
+
×
=25+
=25![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1985174e05ad371e13cf24d244423da4.png)
(1)计算:6÷(-
+
),A同学的计算过程如下:
原式=6×(-
)+6×
=-6+9=3.
请你判断A同学的计算过程是否正确,若不正确,请你写出正确的计算过程.
(2)请你参考例题,用运算律简便计算(请写出具体的解题过程):
999×118
+333×(-
)-999×18
.
例如:(-125
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
解:(-125
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ffd5c35bba71ea54c28622b6cf505d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ffd5c35bba71ea54c28622b6cf505d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ffd5c35bba71ea54c28622b6cf505d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ab44a7dc9c035687a33f6e065392359.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ffd5c35bba71ea54c28622b6cf505d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1985174e05ad371e13cf24d244423da4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1985174e05ad371e13cf24d244423da4.png)
(1)计算:6÷(-
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4b8503f4706b8321e4e79a87eadea84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
原式=6×(-
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf31876698721a199c7c53c6b320aa86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4b8503f4706b8321e4e79a87eadea84.png)
请你判断A同学的计算过程是否正确,若不正确,请你写出正确的计算过程.
(2)请你参考例题,用运算律简便计算(请写出具体的解题过程):
999×118
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7294f5ae2a24ff42e84cd9773b2a7287.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eac97e6740365c85ad857aff85cefbe5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eac97e6740365c85ad857aff85cefbe5.png)
19-20七年级上·湖北恩施·期中 查看更多[7]
湖北省恩施土家族苗族自治州巴东县2019-2020学年七年级上学期期中数学试题(已下线)专题1.42 有理数混合运算31题(培优篇)(专项练习)-2022-2023学年七年级数学上册基础知识专项讲练(人教版)(已下线)专题2.33 有理数混合运算31题(培优篇)(专项练习)-2022-2023学年七年级数学上册基础知识专项讲练(北师大版)江西省宜春实验中学2022-2023学年七年级上学期第一次月考数学试卷(已下线)专题1.49 有理数混合运算50题(培优练)-2023-2024学年七年级数学上册基础知识专项突破讲与练(人教版)(已下线)专题2.48 有理数混合运算50题(培优练)-2023-2024学年七年级数学上册基础知识专项突破讲与练(苏科版)(已下线)专题2.48 有理数混合运算50题(培优练)-2023-2024学年七年级数学上册基础知识专项突破讲与练(北师大版)
更新时间:2019-11-12 18:36:05
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【推荐1】对有理数
、
、
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;②对加法的分配律:
.现对
这种运算作如下定义,规定:
.
(1)这种运算是否满足交换律?
(2)举例说明:这种运算是否满足对加法的分配律?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42dced02b098b04f4ef38d8b83bbfba0.png)
(1)这种运算是否满足交换律?
(2)举例说明:这种运算是否满足对加法的分配律?
您最近一年使用:0次
解答题-计算题
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较难
(0.4)
【推荐1】观察:
;
;
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daa5e9bd516f6282483b92cfe6074623.png)
(1)计算:
;
(2)若
的值是
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的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0669e2d39e920aead4c628021c458fd5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfae2b2b7081fe15a5134b48a9fec6dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5346120387c9dd7f345f257f8d7a2f11.png)
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(1)计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/834d1886af88edbdb28a7a597c84df57.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/807fb54f1c9eafe9504618c4801826e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e163a878e91a915c0ec03a9ea82a4263.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
您最近一年使用:0次
解答题-计算题
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较难
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【推荐2】仔细观察下面的变形规律:
,
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和
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(2)类比发现:
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(3)知识迁移:解关于
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;
(4)规律应用:化简
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/917e937d87a032022ada70cc86add5ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b61dfa259a7cfab28fe63ff7d6211b1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7f4890678dc22224b4d23a8c38fbf11.png)
(1)总结规律:已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ef9bd4b9563242eeccf0be121213a97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe1d026c1d9d02a3dbe59c4e5d673c2.png)
(2)类比发现:
计算
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c887eae327ba27f6b065da701f830ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2924d051ef968d8de7b5690e95b4655.png)
(3)知识迁移:解关于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66f371c3da33ac7936315c3ad3f508f7.png)
(4)规律应用:化简
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/511420c83abcacd3de7e2aab06e3bc21.png)
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