题目内容
求未知数x的值. 5χ-4.5×2=0.5 | ![]() ![]() ![]() |
![]() ![]() | ![]() ![]() ![]() |
解:(1)5χ-4.5×2=0.5,
5x-9=0.5,
5x-9+9=0.5+9,
5x÷5=9.5÷5,
x=1.9;
(2)
:
=1:
x,
×
x=
×1,
x
=![](http://thumb.1010pic.com/pic5/latex/36.png)
,
x=1
;
(3)
:4=χ:
,
4x=
×
,
4x÷4=
÷4,
x=
;
(4)
=
:
,
x=75×
,
x
=![](http://thumb.1010pic.com/pic5/latex/520202.png)
,
x=45.
分析:(1)依据等式的性质,方程两边同时加9,再同时除以5求解,
(2)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以
,
(3)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以4求解,
(4)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以
求解.
点评:本题主要考查学生依据等式的性质,以及比例基本性质解方程的能力.
5x-9=0.5,
5x-9+9=0.5+9,
5x÷5=9.5÷5,
x=1.9;
(2)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/112.png)
![](http://thumb.1010pic.com/pic5/latex/55360.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/55360.png)
x=1
![](http://thumb.1010pic.com/pic5/latex/14.png)
(3)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
4x=
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/602.png)
4x÷4=
![](http://thumb.1010pic.com/pic5/latex/7880.png)
x=
![](http://thumb.1010pic.com/pic5/latex/2132.png)
(4)
![](http://thumb.1010pic.com/pic5/latex/177772.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/2405.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/182079.png)
![](http://thumb.1010pic.com/pic5/latex/520202.png)
![](http://thumb.1010pic.com/pic5/latex/182079.png)
x=45.
分析:(1)依据等式的性质,方程两边同时加9,再同时除以5求解,
(2)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以
![](http://thumb.1010pic.com/pic5/latex/112.png)
(3)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以4求解,
(4)先根据比例基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以
![](http://thumb.1010pic.com/pic5/latex/13.png)
点评:本题主要考查学生依据等式的性质,以及比例基本性质解方程的能力.
![](http://thumb2018.1010pic.com/images/loading.gif)
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