题目内容
已知|a-1|+|2b+3|=0,求3a2-[2ab2-2(ab-
a2b)+ab]+3ab2的值.
解:根据题意得:
,
解得:
,
原式=3a2-[2ab2-2ab+3a2b+ab]+3ab2
=3a2-2ab2+2ab-3a2b-ab+3ab2
=3a2+ab-3a2b+ab2
当a=1,b=-
时,原式=3-
-3×(-
)+
=3-
+
+
=
.
分析:首先根据非负数的性质求得a,b的值,然后把所求的式子化简,然后代入求值即可.
点评:本题考查了非负数的性质以及整式的化简,正确进行化简是关键.
![](http://thumb.1010pic.com/pic5/latex/441442.png)
解得:
![](http://thumb.1010pic.com/pic5/latex/441443.png)
原式=3a2-[2ab2-2ab+3a2b+ab]+3ab2
=3a2-2ab2+2ab-3a2b-ab+3ab2
=3a2+ab-3a2b+ab2
当a=1,b=-
![](http://thumb.1010pic.com/pic5/latex/33.png)
![](http://thumb.1010pic.com/pic5/latex/33.png)
![](http://thumb.1010pic.com/pic5/latex/33.png)
![](http://thumb.1010pic.com/pic5/latex/2321.png)
![](http://thumb.1010pic.com/pic5/latex/33.png)
![](http://thumb.1010pic.com/pic5/latex/190.png)
![](http://thumb.1010pic.com/pic5/latex/2321.png)
![](http://thumb.1010pic.com/pic5/latex/6518.png)
分析:首先根据非负数的性质求得a,b的值,然后把所求的式子化简,然后代入求值即可.
点评:本题考查了非负数的性质以及整式的化简,正确进行化简是关键.
![](http://thumb2018.1010pic.com/images/loading.gif)
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