题目内容
解方程
x-30%x=![数学公式](http://thumb.1010pic.com/pic5/latex/5193.png)
8×(x-
)=![数学公式](http://thumb.1010pic.com/pic5/latex/1180.png)
解:(1)
x-30%x=![](http://thumb.1010pic.com/pic5/latex/5193.png)
x=![](http://thumb.1010pic.com/pic5/latex/5193.png)
x÷
=
÷![](http://thumb.1010pic.com/pic5/latex/32772.png)
x=
;
(2)8×(x-
)=![](http://thumb.1010pic.com/pic5/latex/1180.png)
8×(x-
)÷8=
÷8
x-
+
=
+![](http://thumb.1010pic.com/pic5/latex/365.png)
x=
.
分析:(1)先计算
x-30%x,再根据等式的性质解方程即可;
(2)根据等式的性质2,可得x-
=
,再根据等式的性质1求解.
点评:考查了运用等式的性质解方程.等式的性质1:等式两边同时加上(或减去)同一个数(或式子),结果仍相等.等式的性质2:等式两边同时乘同一个数,或除以同一个不为0的数,结果仍相等.
![](http://thumb.1010pic.com/pic5/latex/5192.png)
![](http://thumb.1010pic.com/pic5/latex/5193.png)
![](http://thumb.1010pic.com/pic5/latex/32772.png)
![](http://thumb.1010pic.com/pic5/latex/5193.png)
![](http://thumb.1010pic.com/pic5/latex/32772.png)
![](http://thumb.1010pic.com/pic5/latex/32772.png)
![](http://thumb.1010pic.com/pic5/latex/5193.png)
![](http://thumb.1010pic.com/pic5/latex/32772.png)
x=
![](http://thumb.1010pic.com/pic5/latex/68678.png)
(2)8×(x-
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/1180.png)
8×(x-
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/1180.png)
x-
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/48256.png)
![](http://thumb.1010pic.com/pic5/latex/365.png)
x=
![](http://thumb.1010pic.com/pic5/latex/146269.png)
分析:(1)先计算
![](http://thumb.1010pic.com/pic5/latex/5192.png)
(2)根据等式的性质2,可得x-
![](http://thumb.1010pic.com/pic5/latex/365.png)
![](http://thumb.1010pic.com/pic5/latex/48256.png)
点评:考查了运用等式的性质解方程.等式的性质1:等式两边同时加上(或减去)同一个数(或式子),结果仍相等.等式的性质2:等式两边同时乘同一个数,或除以同一个不为0的数,结果仍相等.
![](http://thumb2018.1010pic.com/images/loading.gif)
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