题目内容
用你喜欢的方法脱式计算.
(1)128+750÷25×18
(2)(800×
-360)÷40
(3)
×
+
×![数学公式](http://thumb.1010pic.com/pic5/latex/1154.png)
(4)[1-(
-
)]×
.
解:(1)128+750÷25×18
=128+30×18,
=128+540,
=668;
(2)(800×
-360)÷40
=(640-360)÷40,
=280÷40,
=7;
(3)
×
+
×![](http://thumb.1010pic.com/pic5/latex/1154.png)
=(
+
)×
,
=2×
,
=
;
(4)[1-(
-
)]×![](http://thumb.1010pic.com/pic5/latex/168.png)
=[1-
]×
,
=
×
,
=
.
分析:(1)(2)(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
(3)根据乘法分配律计算即可.
点评:当算式中同时含有中括号与小括号时,要注意先算小括号里面的,再算中括号里面的.
=128+30×18,
=128+540,
=668;
(2)(800×
![](http://thumb.1010pic.com/pic5/latex/602.png)
=(640-360)÷40,
=280÷40,
=7;
(3)
![](http://thumb.1010pic.com/pic5/latex/35289.png)
![](http://thumb.1010pic.com/pic5/latex/1154.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/1154.png)
=(
![](http://thumb.1010pic.com/pic5/latex/35289.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/1154.png)
=2×
![](http://thumb.1010pic.com/pic5/latex/1154.png)
=
![](http://thumb.1010pic.com/pic5/latex/9777.png)
(4)[1-(
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
=[1-
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
=
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
=
![](http://thumb.1010pic.com/pic5/latex/13.png)
分析:(1)(2)(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
(3)根据乘法分配律计算即可.
点评:当算式中同时含有中括号与小括号时,要注意先算小括号里面的,再算中括号里面的.
![](http://thumb2018.1010pic.com/images/loading.gif)
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