题目内容
=30
:x=
:![数学公式](http://thumb.1010pic.com/pic5/latex/67856.png)
x+
x=
.
解:(1)
=30,
×15=30×15,
x=450,
(2)
:x=
:
,
x=
×
,
x×
=
×
,
x=
,
(2)
x+
x=
,
x=
,
x×
=
×
,
x=1.
分析:(1)根据等式的性质,把方程的两边同时乘以15,即可解答;
(2)先利用等式的基本性质:两内项之积等于两外项之积,得出
x=
×
,再根据等式的性质两边同时乘
,即可解答;
(3)先把方程的左边计算出来:
x=
,再根据等式的性质,两边同时乘以
,即可解答.
点评:此题考查了利用等式的性质解方程和利用比例的基本性质解比例的方法的灵活应用.
![](http://thumb.1010pic.com/pic5/latex/153276.png)
![](http://thumb.1010pic.com/pic5/latex/153276.png)
x=450,
(2)
![](http://thumb.1010pic.com/pic5/latex/8308.png)
![](http://thumb.1010pic.com/pic5/latex/1207.png)
![](http://thumb.1010pic.com/pic5/latex/67856.png)
![](http://thumb.1010pic.com/pic5/latex/1207.png)
![](http://thumb.1010pic.com/pic5/latex/8308.png)
![](http://thumb.1010pic.com/pic5/latex/67856.png)
![](http://thumb.1010pic.com/pic5/latex/1207.png)
![](http://thumb.1010pic.com/pic5/latex/524.png)
![](http://thumb.1010pic.com/pic5/latex/23630.png)
![](http://thumb.1010pic.com/pic5/latex/524.png)
x=
![](http://thumb.1010pic.com/pic5/latex/731.png)
(2)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/15.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/15.png)
x=1.
分析:(1)根据等式的性质,把方程的两边同时乘以15,即可解答;
(2)先利用等式的基本性质:两内项之积等于两外项之积,得出
![](http://thumb.1010pic.com/pic5/latex/1207.png)
![](http://thumb.1010pic.com/pic5/latex/8308.png)
![](http://thumb.1010pic.com/pic5/latex/67856.png)
![](http://thumb.1010pic.com/pic5/latex/524.png)
(3)先把方程的左边计算出来:
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/155.png)
![](http://thumb.1010pic.com/pic5/latex/15.png)
点评:此题考查了利用等式的性质解方程和利用比例的基本性质解比例的方法的灵活应用.
![](http://thumb2018.1010pic.com/images/loading.gif)
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