许昌平顶山济源2020年高三第二次质量检测
理科数学试题参考答案及解析
一,选择题 CBDCB CDDAA CB
3二填空题(13)14 (14)?20x (1513?) (16)an?n?n?3
321. C
解答:A=(-3,6),B =(1,+?),则AIB =(1,6). 2.B 解答:z?1?2i3?4i??15?2i5,则z??12i5?5.
3.D
解答:
x2?5x?6??x?2??x?3?,x1?2,x22?3,a5?a2ga8?6,a5??6.
4.C
解答:0?sin2?1,b?0,c?1,则b?a?c. 5.B
解答:①③正确,②④错误. 6. C
uBDuur?euuur 解答:设1,PD?e2,
uuuruuuruuuruuuruPDuur 则BP?BD?DP?BD??e1?e2, uuur?uADuur?uDBuur?2uPDuur?uBDuur AB?2e2?e1, uACuur?uADuur?uDCuur ?2e2?e1,
又uBPuur??uABuur??uACuur??????e1??2??2??e2, ?????1, 则??2??2???1,
则???=-12.
7. D
解答:由题知A?a,b?,右焦点F?c,0?, AF?OF?c,
2222 又a?b?c?OA,则OA?c.
OAF为正三角形,则a?ccos60o, 则V 所以e=8. D
解答:li?9. A
解答:必修3:几何概型例3. 10.A
c?2. aZ,i?i?1略S.
f?x??2sin 由已知?=,11.C
121?2?x??2?3??,则选A. ? 解答:令yn??n?1?xn,则xn? 于是方程化为
yn, n?1n?n?1?33yn?2yn?n?0. n?1?n?1? 则f?y?在?0,???上为增函数,且f?n??n43记f?y??n3y3?2y?n, n?1?n?1?则n?yn?n?1?n?2?.则an??yn??n.
?2n?n?0,f?n?1??2?0, n?1又a1?0,
a?a?a?L?a20212?3?4?L?2021则123??1011.5. 2020202012.B
解答:令g?x??f?x??2x,x ef'?x??f?x?f'?x??f?x??2ex则g'?x???2??0, exex
所以,g?x?在?0,???上是减函数.
x则不等式fx?2xe,等价于g?x??0,即g?x??g?2?,则x?2. ??
13.14
22解答:A5?3A2?14.
14.?20x32
33?3?2g?????20x.x??
3n3?x?解答:由2?64,得n?6,中间项为C6?? ?3?15.an?n3?n?3
?3??2??2?解答:由题知,?=???,121 ???????=???32, 2
322
3LL
22???????????nn?1.迭加得 n?1?3??3??3??3??2??2??2???????L????????23n?1n1n?12. 1??则6?n?1???2n?12,?n?6n?6.
21又??n2???1??n?1n?an?2?2an?1?an?6n?6,
则a3?2a2?a1?6?2, a4?2a3?a2?6?3,LL an?2?2an?1?an?6?n?1?,迭加得 an?2?an?1?a2?a1?6?2?3?4L??n?1??, n2?3n则an?2?an?1?6???2?3?4?L??n?1????a2?a1?2?6,
12?3?1则a3?a2??6, 222?3?2a?a3??6, 4 2LL n2?3na?an?1??6,迭加得 n?2 2an?2?a2?则an?2?12??1?22?32?L?n2??3?1?2?3?L?n???6n,? 2?13n?n?1??2n?1??n?n?1??6n?9, 124 则an?n3?n?3.
16.13?解答:在VABD中,由余弦定理,得BD?3,
在四面体ABED中,AE?BD?3,
AD?BE?3,AB?ED?22,
三组对棱长相等,可将四面体ABED放在长方体中,
设长方体的相邻三棱长分别为x,y,z,
则x?y?9,y?z?9,z?x?8,
222222
则x2?y2?z2?13,即2R?13,所以R?13.2
所以,四面体E?ABD外接球的表面积为13?.
E D C
D A B A B
D
E
B
A
解答题: 17(12分)
AECBD解:(1)由正弦定理可得3sinAcosC?3sinCsinA?3sinB. 又A?B?C??,∴B????A?C?, ∴
3sinAcosC?3sinCsinA?3sin?A?C?,
即3sinAsinC?3cosAsinC,
∵0?C??,∴sinC?0,∴tanA?3, 3又∵0?A??,∴A??6.------------------------6分
(2)设AB?x,BD?3x,则CB?4?3x,
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