(6)在等比數(shù)列的值為 (A) 9 (B) 1 (C)2 (D)3 【查看更多】

 

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 在等比數(shù)列的值為（  ）

A．1          B．2            C．3            D． 9

 

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在等比數(shù)列的值為（    ）                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

    A.9           B．1  C．2    D．3

 

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在等比數(shù)列的值為（    ）                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

    A.9           B．1  C．2    D．3

 

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在等比數(shù)列的值為 （   ）

    A．1            B．2                C．3                D． 9  

 

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在等比數(shù)列的值為  （    ）

       A．9                B．1                C．2         D．3

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    2009.3

一、選擇題

（1）B  （2）A  （3）B （4）C （5）B （6）D

（7）D   （8）C  （9）C （10）B （11）A （12）C

二、填空題

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              1,3,5
              三、解答題
              （17）解:（Ⅰ）-            
---------------------------2分
              高三年級人數(shù)為-------------------------3分
              現(xiàn)用分層抽樣的方法在全校抽取48名學(xué)生，應(yīng)在高三年級抽取的人數(shù)為
              (人).                      
--------------------------------------6分
              （Ⅱ）設(shè)“高三年級女生比男生多”為事件，高三年級女生、男生數(shù)記為.
              由（Ⅰ）知且
              則基本事件空間包含的基本事件有
              共11個,    
------------------------------9分
              事件包含的基本事件有
              共5個    
                             
--------------------------------------------------------------11分
              答：高三年級女生比男生多的概率為.  …………………………………………12分
              （18）解：（Ⅰ）  …………2分
              在中，由于，
                                                      …………3分
              又，
                                      
              又，所以，而，因此.…………6分
                 （Ⅱ）由，
              由正弦定理得                                …………8分
              ，
              即，由（Ⅰ）知，所以    …………10分
              由余弦弦定理得 ，     …………11分
              ，
                            
                                …………12分
              （19）（Ⅰ）證明：∵、分別為、的中點，∴.
                   又∵平面平面
              ∴平面                                     
   …………4分
              （Ⅱ）∵，，∴平面.
              又∵，∴平面.
              ∵平面,∴平面平面.              
…………8分
              （Ⅲ）∵平面，∴是三棱錐的高.
              在Rt△中，.
                  在Rt△中，.
               ∵，是的中點，
              ∴,
              故.        ………………12分
              （20）解：（Ⅰ）依題意得
                                          
…………2分 
               解得，                                         
   …………4分
              .       …………6分
                 （Ⅱ）由已知得，                 
…………8分
                                                                      
………………12分
              （21）解：（Ⅰ）
                    令=0,得                       
………2分
              因為，所以可得下表：
              0
              +
              0
              -
              ㄊ
              極大
              ㄋ
                                           
                            ………………4分
              因此必為最大值,∴，因此， 
                   ，
                  即，∴，
               ∴                                       ……………6分
              （Ⅱ）∵，∴等價于，
………8分
               令，則問題就是在上恒成立時，求實數(shù)的取值范圍，為此只需，即，                
…………10分
              解得，所以所求實數(shù)的取值范圍是[0，1].           
………………12分
              （22）解:（Ⅰ）由得，，
              所以直線過定點（3，0），即.                      
…………………2分
               設(shè)橢圓的方程為, 
              則,解得，
              所以橢圓的方程為.                   
……………………5分
              （Ⅱ）因為點在橢圓上運動,所以，     
………………6分
              從而圓心到直線的距離
              所以直線與圓恒相交.                            
……………………9分
              又直線被圓截得的弦長
              ，       …………12分
              由于,所以,則,
              即直線被圓截得的弦長的取值范圍是.  …………………14分
               
              		
              
	
	
              
		
              


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