题目内容
设a≥0,b≥0,且![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/0.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/1.png)
A.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/2.png)
B.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/3.png)
C.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/4.png)
D.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_ST/5.png)
【答案】分析:先把
整理成
•
的形式,把
即可求得a2+(
+
)的值,进而根据均值不等式求得答案.
解答:解:因为a>0,b>0
所以
=
•![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/8.png)
因为a2+(
+
)=
+
=![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/13.png)
所以
≤
×
×
=![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/18.png)
故选C
点评:本题主要考查了基本不等式在最值问题中的应用.解题的关键是整理出均值不等式的形式.
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/0.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/1.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/2.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/3.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/4.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/5.png)
解答:解:因为a>0,b>0
所以
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/6.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/7.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/8.png)
因为a2+(
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/9.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/10.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/11.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/12.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/13.png)
所以
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/14.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/15.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/16.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/17.png)
![](http://thumb.zyjl.cn/pic6/res/gzsx/web/STSource/20131101221625245829847/SYS201311012216252458298003_DA/18.png)
故选C
点评:本题主要考查了基本不等式在最值问题中的应用.解题的关键是整理出均值不等式的形式.
![](http://thumb.zyjl.cn/images/loading.gif)
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