题目内容
解方程
x-![]() ![]() | 2.2x+3.3x=66 | x-![]() ![]() |
7m-2m=12.5 | ![]() ![]() | 9x+7=21.4. |
解:
(1)x-
=
,
x-
+
=
+
,
x=
;
(2)2.2x+3.3x=66,
5.5x=66,
5.5x÷5.5=66÷5.5,
x=12;
(3)x-
=
,
x-
+
=
+
,
x=
;
(4)7m-2m=12.5,
5m=12.5,
5m÷5=12.5÷5,
m=2.5;
(5)
-x=
,
x=
-
,
x=
;
(6)9x+7=21.4,
9x+7-7=21.4-7,
9x=14.4,
9x÷9=14.4÷9,
x=1.6.
分析:(1)等式的两边同时加上
即可;
(2)先计算2.2x+3.3x=5.5x,然后等式的两边同时除以5.5即可;
(3)等式的两边同时加上
即可;
(4)先计算7m-2m=5m,然后等式的两边同时5即可;
(5)根据减数=被减数-差,原式改写成x=
-
,再进一步解答即可;
(6)等式的两边同时减去7,然后等式的两边同时除以9即可.
点评:本题主要考查解方程,根据等式的性质进行解答即可.
(1)x-
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
x-
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
x=
![](http://thumb.1010pic.com/pic5/latex/155.png)
(2)2.2x+3.3x=66,
5.5x=66,
5.5x÷5.5=66÷5.5,
x=12;
(3)x-
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/764.png)
x-
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/7.png)
![](http://thumb.1010pic.com/pic5/latex/764.png)
![](http://thumb.1010pic.com/pic5/latex/7.png)
x=
![](http://thumb.1010pic.com/pic5/latex/13365.png)
(4)7m-2m=12.5,
5m=12.5,
5m÷5=12.5÷5,
m=2.5;
(5)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
x=
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
x=
![](http://thumb.1010pic.com/pic5/latex/112.png)
(6)9x+7=21.4,
9x+7-7=21.4-7,
9x=14.4,
9x÷9=14.4÷9,
x=1.6.
分析:(1)等式的两边同时加上
![](http://thumb.1010pic.com/pic5/latex/8.png)
(2)先计算2.2x+3.3x=5.5x,然后等式的两边同时除以5.5即可;
(3)等式的两边同时加上
![](http://thumb.1010pic.com/pic5/latex/7.png)
(4)先计算7m-2m=5m,然后等式的两边同时5即可;
(5)根据减数=被减数-差,原式改写成x=
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
(6)等式的两边同时减去7,然后等式的两边同时除以9即可.
点评:本题主要考查解方程,根据等式的性质进行解答即可.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目