【答案】
分析:利用開根號(hào)的知識(shí)分別將各選項(xiàng)進(jìn)行化簡(jiǎn),然后即可得出答案.
解答:解:A、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/0.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/1.png)
,故本選項(xiàng)錯(cuò)誤;
B、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/2.png)
=2
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/3.png)
,故本選項(xiàng)正確;
C、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/4.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/5.png)
,故本選項(xiàng)錯(cuò)誤;
D、
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/6.png)
=3
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202454684677335/SYS201311032024546846773002_DA/7.png)
,故本選項(xiàng)錯(cuò)誤.
故選B.
點(diǎn)評(píng):本題考查同類二次根式的知識(shí),屬于基礎(chǔ)題,比較簡(jiǎn)單,注意細(xì)心將各選項(xiàng)分別化簡(jiǎn)后再作答.