【答案】
分析:判定一個二次根式是不是最簡二次根式的方法,就是逐個檢查定義中的兩個條件(①被開方數(shù)不含分母;②被開方數(shù)不含能開得盡方的因數(shù)或因式)是否同時滿足,同時滿足的就是最簡二次根式,否則就不是.
解答:解:A、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/0.png)
符合最簡二次根式的條件;故本選項正確;
B、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/1.png)
=±x,被開方數(shù)里含有能開得盡方的因式x
2;故本選項錯誤;
C、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/2.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/3.png)
=2
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/4.png)
;被開方數(shù)里含有能開得盡方的因數(shù)4;故本選項錯誤;
D、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/5.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/6.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103001229133109706/SYS201311030012291331097000_DA/7.png)
;被開方數(shù)里含有分母;故本選項錯誤.
故選A.
點評:本題主要考查了最簡二次根式的定義,最簡二次根式必須滿足兩個條件:
(1)被開方數(shù)不含分母;
(2)被開方數(shù)不含能開得盡方的因數(shù)或因式.