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    過(guò)x軸上的動(dòng)點(diǎn)A(a,0).引拋物線(xiàn)的兩條切線(xiàn)AP.AQ.P.Q為切點(diǎn)(1)若切線(xiàn)AP.AQ的斜率分別為k1.k2.求證k1?k2為定值;(2)求證:直線(xiàn)PQ過(guò)定點(diǎn); 查看更多

     

    題目列表(包括答案和解析)

    過(guò)x軸上的動(dòng)點(diǎn)A(a,0)引拋物線(xiàn)y=x2+1的兩切線(xiàn)AP,AQ.P,Q為切點(diǎn).
    (I)求切線(xiàn)AP,AQ的方程;
    (Ⅱ)求證直線(xiàn)PQ過(guò)定點(diǎn);
    (III)若a≠0,試求
    S△APQ|OA|
    的最小值.

    查看答案和解析>>

    過(guò)x軸上的動(dòng)點(diǎn)A(a,0)引拋物線(xiàn)y=x2+1的兩切線(xiàn)AP,AQ.P,Q為切點(diǎn).
    (I)求切線(xiàn)AP,AQ的方程;
    (Ⅱ)求證直線(xiàn)PQ過(guò)定點(diǎn);
    (III)若a≠0,試求
    S△APQ
    |OA|
    的最小值.

    查看答案和解析>>

    過(guò)x軸上的動(dòng)點(diǎn)A(a,0)引拋物線(xiàn)y=x2+1的兩切線(xiàn)AP,AQ.P,Q為切點(diǎn).
    (I)求切線(xiàn)AP,AQ的方程;
    (Ⅱ)求證直線(xiàn)PQ過(guò)定點(diǎn);
    (III)若a≠0,試求的最小值.

    查看答案和解析>>

    過(guò)x軸上的動(dòng)點(diǎn)A(a,0)的拋物線(xiàn)y=x2+1引兩切線(xiàn)AP、AQ,P、Q為切點(diǎn).
    (1)若切線(xiàn)AP,AQ的斜率分別為k1,k2,求證:k1•k2為定值;
    (2)求證:直線(xiàn)PQ過(guò)定點(diǎn);
    (3)若a≠0,試求S△APQ:|OA|的最小值.

    查看答案和解析>>

    過(guò)x軸上的動(dòng)點(diǎn)A(a,0)的拋物線(xiàn)y=x2+1引兩切線(xiàn)AP、AQ,P、Q為切點(diǎn).
    (1)若切線(xiàn)AP,AQ的斜率分別為k1,k2,求證:k1k2為定值;
    (2)求證:直線(xiàn)PQ過(guò)定點(diǎn);
    (3)若a≠0,試求S△APQ:|OA|的最小值.

    查看答案和解析>>

    一.選擇題

    1―5  CBABA   6―10  CADDA

    二.填空題

    11.       12.()       13.2          14.         15.

    16.(1,4)

    三.解答題

    數(shù)學(xué)理數(shù)學(xué)理17,解:①         =2(1,0)                      (2分)             

            ?,                                        (4分)

    ?

            cos              =

     

            由,  ,    即B=              (6分)

                                                   (7分)

                                                            (9分)

    ,                                                         (11分)

    的取值范圍是(,1                                                      (13分)

    18.解:①設(shè)雙曲線(xiàn)方程為:  ()                                 (1分)

    由橢圓,求得兩焦點(diǎn),                                           (3分)

    ,又為一條漸近線(xiàn)

    , 解得:                                                     (5分)

                                                        (6分)

    ②設(shè),則                                                      (7分)

          

    ?                             (9分)

    ,  ?              (10分)

                                                    (11分)

      ?

    ?                                        (13分)

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        •   單減區(qū)間為[]        (6分)

           

          ②(i)當(dāng)                                                      (8分)

          (ii)當(dāng)

          ,  (),,

          則有                                                                     (10分)

                                                         (11分)

            在(0,1]上單調(diào)遞減                     (12分)

                                                           (13分)

          20.解:①       

                                                                  (2分)

          從而數(shù)列{}是首項(xiàng)為1,公差為C的等差數(shù)列

            即                                (4分)

           

             即………………※              (6分)

          當(dāng)n=1時(shí),由※得:c<0                                                    (7分)

          當(dāng)n=2時(shí),由※得:                                                 (8分)

          當(dāng)n=3時(shí),由※得:                                                 (9分)

          當(dāng)

              (

                                                    (11分)

                                   (12分)

          綜上分析可知,滿(mǎn)足條件的實(shí)數(shù)c不存在.                                    (13分)

          21.解:①設(shè)過(guò)A作拋物線(xiàn)的切線(xiàn)斜率為K,則切線(xiàn)方程:

                                                                          (2分)

              即

                                                                                                             (3分)

          ②設(shè)   又

               

                                                                   (4分)

          同理可得 

                                                          (5分)

          又兩切點(diǎn)交于 

                                         (6分)

          ③由  可得:

           

                                                          (8分)

                            (9分)

           

          當(dāng) 

          當(dāng) 

                                                               (11分)

          當(dāng)且僅當(dāng),取 “=”,此時(shí)

                                                 (12分)

          22.①證明:由,    

            即證

            ()                                    (1分)

          當(dāng)  

                即:                          (3分)

            ()    

          當(dāng)   

             

                                                                   (6分)

          ②由      

          數(shù)列

                                                        (8分)

          由①可知, 

                              (10分)

          由錯(cuò)位相減法得:                                       (11分)

                                              (12分)