参考答案
一、选择题
1-4: DAAD 5-8:BDBA
二、填空题
9. ?216 10. 11. -1 12.8 13.[1,13] 3314.(0,1)
三、解答题
15.解:(1)由题图得f(0)???33,所以cos??,因为0???,故??.
26227??13???x0??, 666由于f(x)的最小正周期等于2,所以由题图可知1?x0?2,故
?33?cos?x?sin?x?3sin(??x). 22611??2?1?,]时,????x?.所以??sin(??x)?1, 2366326??1故??x?,即x??时,g(x)取得最大值3; 623当x?[?当
?6??x???6,即x?13时,g(x)取得最小值?. 3211C2C6316.解:(1)P(A)??; 2C871122112C2C6?C2C6C4C2?C2139(2)∵P(X?1)?;; ?P(X?2)???222C828C8C628222112222C6C6C4C2C2?C2C4C2C251;. P(X?3)?2?2??P(X?4)?????22222C8C6C428C8C6C4C228∴X的分布列为
X 1 2 3 4 139 28281395125E(x)?1??2??3??4??.
2828282814P 5 281 28????????????17.试题解析:依题意,OF?平面ABCD,如图,以O为点,分别以AD,BAOF,的方向
为x轴,y轴、z轴的正方向建立空间直角坐标系,依题意可得O(0,0,0),A(?1,1,0),
B(?1,?1,0),C(1,?1,0),D(1,1,0),E(?1,?1,2),F(0,0,2),G(?1,0,0).
????????(1)证明:依题意AD?(2,0,0),AF?(1,?1,2).
??????????2x?0?n1?AD?0设n1?(x,y,z)为平面ADF的法向量,则??????,即?. ??x?y?2z?0??n1?AF?0????????????不妨设z?1,可得n1?(0,2,1),又EG?(0,1,?2),可得EG?n1?0,
又因为直线EG?平面ADF,所以EG//平面ADF.
????(2)解:易证:OA?(?1,1,0)为平面OEF的一个法向量. ????????依题意EF?(1,1,0),CF?(?1,1,2).
????????????x?y?0?n2?EF?0设n2?(x,y,z)为平面CEF的法向量,则???,即. ????????x?y?2z?0??n2?CF?0???不妨设x?1,可得n2?(1,?1,1).
?????????????????????3OA?n26??????因此有cosOA,n2?????,于是sinOA,n2?,
33|OA|?|n2|所以,二面角O?EF?C的正弦值为
3. 3????22(3)解:由AH?HF,得AH?AF.因为AF?(1,?1,2),所以
35????2????224????284334AH?AF?(,?,),有H(?,,),从而BH?(,,),因此
5555555555??????????????7BH?n27???.所以直线BH与平面CEF所成角的正弦值为. cosBH,n2???????2121|BH|?n2|18.解:(1)证明:由题意可得f(an)?4?2(n?1)?2n?2, 即logkan?2n?2, ∴an?k2n?2,
an?1k2(n?1)?2∴?2n?2?k2.
ank∵常数k?0且k?1, ∴k为非零常数,
∴数列{an}是以k为首项,k为公比的等比数列. (2)当k?42211时,an?n?1,f(an)?2n?2,
2211(1?n)2n?2?42?n2?3n?1?1, 所以Sn?n?4n?112221?2112因为n?1,所以n?3n??n?1是递增数列,
221117因而最小值为S1?1?3???.
244由(1)知,cn?anlgan?(2n?2)?k2n?2lgk, 要使cn?cn?1对一切n?N成立,
即(n?1)lgk?(n?2)?k2?lgk对一切n?N恒成立;
*当k?1时,lgk?0,n?1?(n?2)k2对一切n?N恒成立,
**n?1)min. n?2n?11?1?∵单调递增, n?2n?2n?12)min?. ∴当n?1时,(n?23只需k<(2∴k<226,且0?k?1,∴0?k?. 33综上所述,存在实数k?(0,6)∪(1,??)满足条件. 319.解:(1)∵AC1?AC2,C1(0,b),C2(0,?b),A(1,0),
??????????2∴AC1?AC2?1?b2?0,∴b?1.
∵2c?22,解得c?2,∴a2?b2?c2?3.
x2?y2?1. ∴椭圆E的方程为3离心率e?c26. ??a33(2)m,n之间满足数量关系m?n?1.下面给出证明:
①当取M(3,0),N(?3,0)时,kMB?2?n22,kBP?,kNB?.
3?m3?33?3∵直线MB,BP,NB的斜率依次成等差数列,∴2?2?n22??,化为:3?m3?33?3m?n?1.
②当直线MN的斜率不为0时,设直线MN的方程为:ty?1?x,M(x1,y1),N(x2,y2).
?ty?1?x?22联立?x2,化为:(t?3)y?2ty?2?0, 2??y?1?3∴y1?y2??2t?2yy?,. 12t2?3t2?3kMB?2?ny1?2y?2,kBP?,kNB?2.
3?mx2?3x1?3∵直线MB,BP,NB的斜率依次成等差数列, ∴2?2?ny1?2y2?2, ??3?mx1?3x2?3由于
y1?2y2?2(y1?2)(ty2?2)?(y2?2)(ty1?2) ??x1?3x2?3(ty1?2)(ty1?2)?∴
2ty1y2?(2t?2)(y1?y2)?8?2, 2ty1y2?2t(y1?y2)?42?n?1,化为:m?n?1. 3?m120.解:(1)h'(x)??2a?,
xa?1时,h(x)??2x?lnx,h'(x)??2?13,h(2)??4?ln2,h'(2)??. x2h(x)在(2,g(2))处的切线方程为3x?2y?2ln2?2?0.
1ax2?2ax?1(x?0), (2)f'(x)?ax?2a??xxf'(x)?0?ax2?2ax?1?0,
????4a2?4a?0?所以?x1?x2?2,所以1?a?2.
?11?x1x2??a2?a?a2?aa?a2?a(3)由ax?2ax?1?0,解得x1?,x2?,
aa2∵1?a?2,∴x2?1?1?12. ?1?a2而f(x)在(x2??)上单调递增,∴f(x)在[1?2,2]上单调递增. 2∴在[1?2,2]上,f(x)max?f(2)??2a?ln2. 22,2],使不等式f(x0)?ln(a?1)?m(a2?1)?(a?1)?2ln2恒成2所以,“存在x0?[1?立”等价于“不等式?2a?ln2?ln(a?1)?m(a2?1)?(a?1)?2ln2恒成立”, 即,不等式ln(a?1)?ma2?a?m?ln2?1?0对任意的a(1?a?2)恒成立. 令g(a)?ln(a?1)?ma2?a?m?ln2?1,则g(1)?0.
1?2ma2?2ma?ag'(a)??2ma?1?.
a?1a?1?2ma2?2ma?a?0,g(a)在(1,2)上递减. ①当m?0时,g'(a)?a?1g(a)?g(1)?0,不合题意.
?2ma(a?1?②当m?0时,g'(a)?若1??(1?a?11)2m.
11),记t?min(2,?1?),则g(a)在(1,t)上递减. 2m2m在此区间上有g(a)?g(1)?0,不合题意.
?m?01?m??因此有?,解得, 14?1??1?2m?所以,实数m的取值范围为(??,?].
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