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(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

  1. 
   
    
    
    
    
    
    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