题目内容
解方程.
3x-29=19 | 3×2-6x=4.2 | x-![]() ![]() | ![]() ![]() |
解:(1)3x-29=19,
3x-29+29=19+29,
3x÷3=48÷3,
x=16;
(2)3×2-6x=4.2,
6-6x=4.2,
6-6x+6x-4.2=4.2+6x-4.2,
6x÷6=1.8÷6,
x=0.3;
(3)x-
=
,
x-
+
=
+
,
x=
;
(4)
+x=
,
+x-
=
-
,
x=
.
分析:(1)依据等式的性质,方程两边同时加39,再同时除以3求解;
(2)先化简方程,再依据等式的性质,方程两边同时加6x-4.2,再同时除以6求解;
(3)依据等式的性质,方程两边同时加
求解.
(4)依据等式的性质,方程两边同时减去
求解.
点评:本题主要考查学生依据等式的性质解方程的能力,解答时注意对齐等号.
3x-29+29=19+29,
3x÷3=48÷3,
x=16;
(2)3×2-6x=4.2,
6-6x=4.2,
6-6x+6x-4.2=4.2+6x-4.2,
6x÷6=1.8÷6,
x=0.3;
(3)x-
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/35.png)
x-
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/35.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
x=
![](http://thumb.1010pic.com/pic5/latex/35004.png)
(4)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/450.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
![](http://thumb.1010pic.com/pic5/latex/450.png)
![](http://thumb.1010pic.com/pic5/latex/597.png)
x=
![](http://thumb.1010pic.com/pic5/latex/2362.png)
分析:(1)依据等式的性质,方程两边同时加39,再同时除以3求解;
(2)先化简方程,再依据等式的性质,方程两边同时加6x-4.2,再同时除以6求解;
(3)依据等式的性质,方程两边同时加
![](http://thumb.1010pic.com/pic5/latex/8.png)
(4)依据等式的性质,方程两边同时减去
![](http://thumb.1010pic.com/pic5/latex/597.png)
点评:本题主要考查学生依据等式的性质解方程的能力,解答时注意对齐等号.
![](http://thumb2018.1010pic.com/images/loading.gif)
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