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

 

題目列表(包括答案和解析)

 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名學生，應在高三年級抽取的人數(shù)為
      (人).                      
--------------------------------------6分
      （Ⅱ）設“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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