题目内容
[2.25+(3
-1.21×
)]÷40%
1
+2
+3
+4
+…+10![数学公式](http://thumb.1010pic.com/pic5/latex/10387.png)
(5.4×
+6
÷0.75)×125.5
(1+
+
+
)×(
+
+
+
)-( 1+
+
+
+
)×(
+
+
)
解:(1)[2.25+(3
-1.21×
)]÷40%,
=[2.25+(3.6-0.55)]÷0.4,
=[2.25+3.05]÷0.4,
=5.3÷0.4,
=13.25;
(2)1
+2
+3
+4
+…+10
,
=(1+
)+(2+
)+(3+
)+(4+
)+…+(10+
),
=(1+2+3+4+…+10)+(
+
+
+
+…+
)
=(1+10)×10÷2+(
+
+
+
+…+
),
=11×10÷2+(1-
+
-
+
-
+
-
+…+
-
),
=55+(1-
),
=55+
,
=55
;
(3)(5.4×
+6
÷0.75)×125.5
=(5.4×
+6.6÷0.75)×125.5
=(7.2+8.8)×125.5,
=16×125.5,
=2008;
(4)(1+
+
+
)×(
+
+
+
)-(1+
+
+
+
)×(
+
+
),
=(1+
+
+
)×(
+
+
+
)-[1×(
+
+
)+(
+
+
+
)×(
+
+
)],
=(1+
+
+
)×(
+
+
+
)-(
+
+
)-(
+
+
+
)×(
+
+
),
=(
+
+
+
)×[(1+
+
+
)-(
+
+
)]-(
+
+
),
=(
+
+
+
)-(
+
+
),
=
.
分析:(1)先计算小括号里面乘法,再计算小括号里面除法,再计算中括号里面的加法,最后计算除法;
(2)把带分数写成整数加分数的形式,整数结合一起,根据求和公式即可,分数放在一起,把分母写成两个相邻的整数的乘积,再根据分数的拆项公式
=
-
进行计算即可;
(3)先把带分数化成假分数,先计算小括号里面的乘法和除法,再计算小括号里面的加法,最后计算小括号外面的乘法;
(4)把
+
+
+
看作一个整体,根据乘法分配律进行简算即可.
点评:根据题意,要按照它们的运算顺序进行计算,能简算的要简算.
![](http://thumb.1010pic.com/pic5/latex/14.png)
![](http://thumb.1010pic.com/pic5/latex/6232.png)
=[2.25+(3.6-0.55)]÷0.4,
=[2.25+3.05]÷0.4,
=5.3÷0.4,
=13.25;
(2)1
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/6.png)
![](http://thumb.1010pic.com/pic5/latex/496.png)
![](http://thumb.1010pic.com/pic5/latex/10387.png)
=(1+
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/6.png)
![](http://thumb.1010pic.com/pic5/latex/496.png)
![](http://thumb.1010pic.com/pic5/latex/10387.png)
=(1+2+3+4+…+10)+(
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/6.png)
![](http://thumb.1010pic.com/pic5/latex/496.png)
![](http://thumb.1010pic.com/pic5/latex/10387.png)
=(1+10)×10÷2+(
![](http://thumb.1010pic.com/pic5/latex/6902.png)
![](http://thumb.1010pic.com/pic5/latex/6903.png)
![](http://thumb.1010pic.com/pic5/latex/12344.png)
![](http://thumb.1010pic.com/pic5/latex/17653.png)
![](http://thumb.1010pic.com/pic5/latex/59301.png)
=11×10÷2+(1-
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/63.png)
![](http://thumb.1010pic.com/pic5/latex/2873.png)
=55+(1-
![](http://thumb.1010pic.com/pic5/latex/2873.png)
=55+
![](http://thumb.1010pic.com/pic5/latex/11220.png)
=55
![](http://thumb.1010pic.com/pic5/latex/11220.png)
(3)(5.4×
![](http://thumb.1010pic.com/pic5/latex/66680.png)
![](http://thumb.1010pic.com/pic5/latex/14.png)
=(5.4×
![](http://thumb.1010pic.com/pic5/latex/304.png)
=(7.2+8.8)×125.5,
=16×125.5,
=2008;
(4)(1+
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
=(1+
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
=(1+
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
=(
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
=(
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
=
![](http://thumb.1010pic.com/pic5/latex/155.png)
分析:(1)先计算小括号里面乘法,再计算小括号里面除法,再计算中括号里面的加法,最后计算除法;
(2)把带分数写成整数加分数的形式,整数结合一起,根据求和公式即可,分数放在一起,把分母写成两个相邻的整数的乘积,再根据分数的拆项公式
![](http://thumb.1010pic.com/pic5/latex/2104.png)
![](http://thumb.1010pic.com/pic5/latex/656.png)
![](http://thumb.1010pic.com/pic5/latex/829.png)
(3)先把带分数化成假分数,先计算小括号里面的乘法和除法,再计算小括号里面的加法,最后计算小括号外面的乘法;
(4)把
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
点评:根据题意,要按照它们的运算顺序进行计算,能简算的要简算.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
计算下面各题.
(分数,先填分子,后填分母)
(1)56 ×100= |
(2)25 ×40= |
(3)1.25 ×8= |
(4) ![]() ![]() |
口算
0.6+0.4= | 1+2.25= | 1.6+0.8= | 1.6×5= |
0.13×0.5= | 0.8×0.7= | 2-1.09= | 6.3÷2.1= |
10.6×3= | 6.8×0.12= | 14.76÷0.12= | 3.6÷7.2= |
13.2+11.8= | 12÷0.3= | 2.25×4= | 3.1+3.9= |