题目内容
用你喜欢的方法脱式计算.
-
+
+
-
-![数学公式](http://thumb.1010pic.com/pic5/latex/7880.png)
-
+(
-
)
-(
+
)+
.
解:(1)
-
+
=
-
,
=1-
,
=
;
(2)
+
-
-![](http://thumb.1010pic.com/pic5/latex/7880.png)
=
-
+(
),
=
+0,
=
;
(3)
-
+(
-
)
=(
)-(
),
=
-1,
=
;
(4)
-(
+
)+![](http://thumb.1010pic.com/pic5/latex/365.png)
=
-(
)
,
=
,
=
,
=
.
分析:算式(1)可以根据加法交换律进行计算;
算式(2)可以根据加法交换律与结合律进行计算;
算式(3)可以根据加法交换律与结合律以及一个数减两个数等于减去这两个数的和的减法性质进行简便计算.
算式(4)根据四则混合运算的运算顺序计算即可.
点评:完成有关于分数加减法的算式要注意通分、约分,结果要化为最简分数.
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
=
![](http://thumb.1010pic.com/pic5/latex/291526.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
=1-
![](http://thumb.1010pic.com/pic5/latex/2405.png)
=
![](http://thumb.1010pic.com/pic5/latex/3724.png)
(2)
![](http://thumb.1010pic.com/pic5/latex/1112.png)
![](http://thumb.1010pic.com/pic5/latex/7880.png)
![](http://thumb.1010pic.com/pic5/latex/2367.png)
![](http://thumb.1010pic.com/pic5/latex/7880.png)
=
![](http://thumb.1010pic.com/pic5/latex/1112.png)
![](http://thumb.1010pic.com/pic5/latex/2367.png)
![](http://thumb.1010pic.com/pic5/latex/451518.png)
=
![](http://thumb.1010pic.com/pic5/latex/451519.png)
=
![](http://thumb.1010pic.com/pic5/latex/283611.png)
(3)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/14.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
=(
![](http://thumb.1010pic.com/pic5/latex/48067.png)
![](http://thumb.1010pic.com/pic5/latex/153121.png)
=
![](http://thumb.1010pic.com/pic5/latex/1412.png)
=
![](http://thumb.1010pic.com/pic5/latex/335.png)
(4)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/3856.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
=
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/451520.png)
![](http://thumb.1010pic.com/pic5/latex/157876.png)
=
![](http://thumb.1010pic.com/pic5/latex/451521.png)
=
![](http://thumb.1010pic.com/pic5/latex/451522.png)
=
![](http://thumb.1010pic.com/pic5/latex/25378.png)
分析:算式(1)可以根据加法交换律进行计算;
算式(2)可以根据加法交换律与结合律进行计算;
算式(3)可以根据加法交换律与结合律以及一个数减两个数等于减去这两个数的和的减法性质进行简便计算.
算式(4)根据四则混合运算的运算顺序计算即可.
点评:完成有关于分数加减法的算式要注意通分、约分,结果要化为最简分数.
![](http://thumb2018.1010pic.com/images/loading.gif)
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