题目内容
(2010•成都一模)解答下列各题:(1)计算:
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_ST/0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_ST/1.png)
(2)先化简再求值:
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_ST/2.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_ST/3.png)
【答案】分析:(1)根据实数的运算法则计算.(2)根据约分的方法和二次根式的性质进行化简,最后代入计算.
解答:(1)解:原式=
-
+2×
+1-
=1,
(2)解:原式=
=a+b,
当
,
原式=
.
点评:本题主要考查实数的运算和二次根式的化简求值,在计算时应该仔细,特别注意特殊三角函数值.
解答:(1)解:原式=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/0.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/1.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/2.png)
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/3.png)
(2)解:原式=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/4.png)
当
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/5.png)
原式=
![](http://thumb.1010pic.com/pic6/res/czsx/web/STSource/20131021230512158960018/SYS201310212305121589600019_DA/6.png)
点评:本题主要考查实数的运算和二次根式的化简求值,在计算时应该仔细,特别注意特殊三角函数值.
![](http://thumb2018.1010pic.com/images/loading.gif)
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