题目内容
解方程.
(1)![]() ![]() | (2)![]() ![]() | (3)19![]() ![]() | (4)12.48:X=![]() ![]() |
解:(1)
x-
x=1.4,
x=1.4,
x÷
=1.4÷
,
x=3;
(2)
x-5=
,
x-5+5=
+5,
x=
,
x÷
=
÷
,
x=22;
(3)19
x+3
×2=7,
19
x+7=7,
19
x+7-7=7-7,
19
x=0,
19
x÷19
=0÷19
,
x=0;
(4)12.48:x=
:
,
x=12.48×
,
x÷
=12.48×
÷
,
x=9.36.
分析:(1)(2)(3)先化简方程,再依据等式的性质,“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”求解;
(4)先根据比例的基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质求解.
点评:本题主要考查学生运用等式的性质及比例基本性质解方程的能力,注意等号对齐.
![](http://thumb.1010pic.com/pic5/latex/168.png)
![](http://thumb.1010pic.com/pic5/latex/36.png)
![](http://thumb.1010pic.com/pic5/latex/2131.png)
![](http://thumb.1010pic.com/pic5/latex/2131.png)
![](http://thumb.1010pic.com/pic5/latex/2131.png)
![](http://thumb.1010pic.com/pic5/latex/2131.png)
x=3;
(2)
![](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/13.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/3523.png)
![](http://thumb.1010pic.com/pic5/latex/287829.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/3523.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
x=22;
(3)19
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
19
![](http://thumb.1010pic.com/pic5/latex/13.png)
19
![](http://thumb.1010pic.com/pic5/latex/13.png)
19
![](http://thumb.1010pic.com/pic5/latex/13.png)
19
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
![](http://thumb.1010pic.com/pic5/latex/13.png)
x=0;
(4)12.48:x=
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
![](http://thumb.1010pic.com/pic5/latex/96.png)
![](http://thumb.1010pic.com/pic5/latex/8.png)
x=9.36.
分析:(1)(2)(3)先化简方程,再依据等式的性质,“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”求解;
(4)先根据比例的基本性质,两内项之积等于两外项之积,化简方程,再依据等式的性质求解.
点评:本题主要考查学生运用等式的性质及比例基本性质解方程的能力,注意等号对齐.
![](http://thumb2018.1010pic.com/images/loading.gif)
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