【答案】
分析:(1)本題涉及零指數(shù)冪、負(fù)整數(shù)指數(shù)冪、特殊角的三角函數(shù)值、二次根式化簡(jiǎn)四個(gè)考點(diǎn).在計(jì)算時(shí),需要針對(duì)每個(gè)考點(diǎn)分別進(jìn)行計(jì)算,然后根據(jù)實(shí)數(shù)的運(yùn)算法則求得計(jì)算結(jié)果;
(2)將分式的分子、分母因式分解,約分、通分,再代值計(jì)算.
解答:解:(1)原式=3
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/0.png)
-1-3×
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/1.png)
+4-(2-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/2.png)
)
=3
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/3.png)
-1-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/4.png)
+4-2+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/5.png)
=3
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/6.png)
+1;
(2)原式=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/7.png)
•
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/8.png)
-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/9.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/10.png)
-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/11.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/12.png)
;
當(dāng)x=2-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/13.png)
時(shí),
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/14.png)
=
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131022163850605945039/SYS201310221638506059450014_DA/15.png)
.
點(diǎn)評(píng):本題考查實(shí)數(shù)的綜合運(yùn)算能力,是各地中考題中常見(jiàn)的計(jì)算題型.解決此類(lèi)題目的關(guān)鍵是熟記特殊角的三角函數(shù)值,熟練掌握負(fù)整數(shù)指數(shù)冪、零指數(shù)冪、二次根式、絕對(duì)值等考點(diǎn)的運(yùn)算.同時(shí)考查了分式的化簡(jiǎn)運(yùn)算.關(guān)鍵是根據(jù)分式化簡(jiǎn)的順序,因式分解,約分、通分,再代值計(jì)算.