【答案】
分析:(1)此題有兩種不同的做法,第一個(gè)方法是把分子與分母同時(shí)乘以分母的有理化因式(
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/0.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/1.png)
),再進(jìn)行計(jì)算即可;第二個(gè)計(jì)算方法是把分子進(jìn)行整理,再利用平方差公式進(jìn)行分解,即可求出結(jié)果.
(2)先把分子與分母進(jìn)行有理化,再進(jìn)行統(tǒng)分,然后把分子中的各項(xiàng)進(jìn)行抵消,即可求出答案.
解答:解:(1)方法一:
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/2.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/3.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/4.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/5.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/6.png)
;
方法二:
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/7.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/8.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/9.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/10.png)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/11.png)
;
(2)
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/12.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/13.png)
+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/14.png)
+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/15.png)
+…+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/16.png)
,
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/17.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/18.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103202433767267893/SYS201311032024337672678022_DA/19.png)
.
點(diǎn)評(píng):此題考查了分母有理化,利用平方差公式找出分子與分母中的有理化因式,再進(jìn)行分母有理化是解題的關(guān)鍵.