题目内容
(2002•内江)已知a+b=-8,ab=8,化简![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_ST/0.png)
【答案】分析:∵a+b=-8,ab=8,∴a,b同为负数,化简原式,再代入求值.
解答:解:∵a+b=-8,ab=8,∴a,b同为负数,
故原式=b
+a
=(
-
)
,
即-![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/5.png)
=-
×
=-12
.
点评:解答此题的关键是要首先确定a,b的符号,再进行计算.注意整体代入思想的运用.
解答:解:∵a+b=-8,ab=8,∴a,b同为负数,
故原式=b
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/1.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/2.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/3.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/4.png)
即-
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/5.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/6.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/7.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/8.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021232506107252803/SYS201310212325061072528025_DA/9.png)
点评:解答此题的关键是要首先确定a,b的符号,再进行计算.注意整体代入思想的运用.
![](http://thumb2018.1010pic.com/images/loading.gif)
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