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鞍山市普通高中 2024—2025学年高三第一次质量检测
数学科参考答案
一、选择题:
1~5、DBDAB . 6~8、DAC 9、ACD 10、BC 11、ACD
二、填空题:
3
12、12 13、 14、 2 2 或 4 2 3 或 2 3
5
三、解答题:
15.解:(1)取 AD 中点 E ,连接 PE ,因为平面 PAD ⊥平面 ABCD,平面 PAD 平面 ABCD = AD ,
PE 平面 PAD ,在等边 PAD 中, PE ⊥ AD,
所以 PE ⊥平面 ABCD, ·························· 3分
1 4 3 4 3
PE = 3 ,VP ABCD = 4 3 = ,所以四棱锥 P ABCD的体积为 ·· 6分
3 3 3
(2)取 BC 中点 F ,连接 EF ,则 EF ⊥ AD ,以 E 为坐标原点,分别以 EA, EF , EP 的方向
为 x,y,z轴的正方向, A(1,0,0), P(0,0, 3),C( 1,2,0), B(1,2,0),
AP = ( 1,0, 3), AC = ( 2,2,0) ······················· 7分
设 n1 = (x1, y1, z1)为平面 APC 的法向量,则有
n1 AP = x1 + 3z1 = 0
,令 z =1,得 n1 = ( 3, 3,1), ············ 10分
n1 AC = 2x1 + 2y1 = 0
取 n2 = (0,0,1)为平面 ABC 的法向量,
n n 1 7
cos n1,n =
1 2
2 = = ···················· 12分
| n1 | | n2 | 7 7
由图可知,二面角 P AC B的大小为钝角,
7
二面角 P AC B的余弦值为 ················ 13分
7
1
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16(1)
关注 不关注 合计
男生 55 5 60
女生 20 10 30
合计 75 15 90
···································· 3分
90(55 10 20 5)2
2 = = 9 6.635
60 30 75 15
能有 99%的把握认为该校学生对探月工程的关注与性别有关 ········· 6 分
(2)记这 4个问题为 a,b,c,d ,记振华答对 a,b,c,d 的事件分别记为 A, B,C, D ,分别记按方案一、
二晋级的概率为 P1, P2 ,则 P1 = P(ABCD) + P(ABCD) + P(ABCD) + P(ABCD) + P(ABCD)
2 3 1 2 2 1 1 14= ( ) 2 + ( ) 3 = ····················· 10分
3 2 3 2 3 27
1 1 1 1 1 1
P2 = P(AB) + P(AC) + P(AD) + P(BC) + P(BD) + P(CD)
6 6 6 6 6 6
1 2 2 2 1 7= [( ) 3+ 3] = ······················· 13分
6 3 3 2 18
14 7
因为 ,振华选择方案一晋级的可能性更大 ············· 15分
27 18
c = 2
c 2 a = 3
17 解:(1)由题意 = ,可得 ,
a 3 b = 5
a
2 = b2 + c2
x2 y2
椭圆C : + =1 ··························· 3分
9 5
x 2 y 2
设M (x1 , y1) ,
1 + 1 =1,又 A1( 3,0), A2 (3,0) ,
9 5
5
5 x 2
y y 2 1
k k = 1 1
y1 9 5
A1M A2M
= = =
x1 + 3 x1 3 x
2 2
1 9 x1 9 9
2
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5
所以, kMA kMA 为定值 ························ 6分1 2 9
y y
(2) kA P = k =
P
MA ,kA P = kA N =
P , kA = 3k ·············· 8分 1 1 9 2 2 3 2
N MA1
5
kA M kA N = kA M 3kA M = 2 2 2 1 3
x2 y2
设直线MN : x = my + t ,代入 + =1,得 (5m2 + 9)y2 +10mty + 5t2 45 = 0,
9 5
2 2
M (x1, y1), N(x2 , y2 ) ,则 0,5m + 9 t
10mt
y1 + y2 =
5m
2 + 9
且有 , ························· 10分
5t
2 45
y y =
1 2
5m2 + 9
y y y y 5
kA M k =
1 2 = 1 2 =
2 A2N x1 3 x 3 m
2
2 y1y2 +m(t 3)(y1 + y2 ) + (t 3)
2 3
5t2 45 5 3
所以 = ,可得 t = 或 3(舍) ················ 14分
9t2 54t + 81 3 2
3
直线MN 过定点( ,0) ························· 15分
2
y
法二:设 P(6, yP ) ,直线 A1P : y =
P (x + 3)
9
y
y =
P (x + 3)
9
2 2
由 x y+ =1 ,得
9 5
(45 + y 2 2p )x +16y
2
p x + 9y
2
p 405 = 0
9y 2 405 3y 2 +135 30y
= 72900 0,所以, 3x = P , x = P PM M , yM = ···· 10分
45 + y 2 45 + y 2P P 45 + y
2
P
3y 2 15 10y
同理 x = P , y = PN N ······················ 11分
5 + y 2P 5 + y
2
P
3
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2
y y 20yp (yp +15) 20yp
直线MN 的斜率存在时, kMN =
M N = =
xM x 3y
4
N p + 675 3(y
2
p 15)
10yp 20yp 3y
2
p 15
MN : y + = (x ) ,令 y = 0 ,
5 + y 2p 3(y
2
p 15) 5 + y
2
p
3y 2p 15 3(y
2
p 15) 3y
2
p +15 3
x = = = ·················· 13分
5 + y 2p 2(5 + y
2
p ) 2(5 + y
2
p ) 2
3y 2 +135 3y 2 15 3
当 MN 的斜率不存在时,, x = PM = x =
P 2
N , yP =15, xM = xN =
45 + y 2P 5 + y
2 2
P
3
直线MN 过定点( ,0) ························· 15分
2
a
18.(1) f (x) = e2x x , x [0,+ )
2
f (x) = ae2x 1, x (0,+ ) ,(注:导函数的定义域按[0,+ ) 写不扣分,下同)
···································· 1分
① a 0 时, f (x) 0 恒成立,所以 f (x) 在 [0,+ ) 上递减(注:写 (0,+ ) 上递增不扣分,下同)
···································· 2分
② a 1时, f (x) e2x 1 0 (x 0)恒成立,所以 f (x) 在[0,+ ) 上递增
···································· 3分
1 1
③ 0 a 1时,令 f (x) = 0 得 x = ln
2 a
1 1 1 1
x (0, ln ), f (x) 0 , f (x) 单调递减, x ( ln ,+ ), f (x) 0, f (x) 单调递增
2 a 2 a
···································· 5分
综上: a 0 f (x) 在[0,+ ) 上单调递减 ,
a 1时 f (x) 在[0,+ ) 上递增,
1 1 1 1
a (0,1) 时, f (x) 在 (0, ln )上单调递减, f (x) 在 ( ln ,+ ) 上单调递增
2 a 2 a
1 1
(2)因为 f (x) 不是单调函数,由(1)知, a (0,1) ,且 f (x) 在 (0, ln )上单调递减, f (x) 在
2 a
4
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1 1 1 1 1 1
( ln ,+ ) 上单调递增,要使得 f (x) 有 2个零点 x1、x2,则必有 f ( ln ) = (1 ln ) 0,
2 a 2 a 2 a
1
所以, a (0, ) , ···························· 7分
e
1 a
又当 a (0, ) 时, f (0) = 0
e 2
2
x 2 x 2x x
2
先证: e x (x 0) ,令 (x) = , (x 0), (x) = , (x 0),令 (x) 0,0 x 2,
ex ex
4
令 (x) 0, x 2 , (x) 在 (0,2) 上单调递增,在 (2,+ )上单调递减,所以, (x) (2) = 1
e2
所以 ex x2
x
(x 0) 成立,所以, x 2ln x(x 0) ,即: ln x x(x 0) 成立,
2
1
1 1 1 1 a 1 1
取 x0 = 则有 ln (x 0),且 f (x
a
0 ) = (e ) 0 ,所以 a (0, ) 时, f (x) 有 2 个零
2a 2a 2 a 2 a2 e
点
1
综上: a (0, ) ····························· 10分
e
x 3a a 3a(3)令 F (x) = f (x) (1 a)e ( 1)cos x = e2x x (1 a)ex ( 1)cos x , x [0,+ )
2 2 2
则 F (x) 0恒成立,且 F (0) = 0
2x 3aF (x) = ae 1+ (a 1)ex + ( 1)sin x, x [0,+ ), F (0) = 2a 2 ······· 11分
2
3a
① a 1时, F (x) ae2x 1+ ( 1)sin x,当 x [0, ]时, F (x) 0,当 x ( ,+ )时,
2
3a
F (x) ae2x 1 ( 1) = ae2x
3a 3
= a(e2x ) 0
2 2 2
x [0,+ )时, F (x) 0恒成立,所以, F(x)在[0,+ ) 上递增,
所以, F(x) F(0) = 0 ,符合题意 ······················ 13分
a
② a 0 时, F( ) = e + (a 1)e 2 0 ,与题意不符,舍去 ········ 14分
2 2 2
③ 0 a 1时, F (0) = 2a 2 0 , x 0 时,
5
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3a 3a 3a
F (x) ae2x 1+ (a 1)ex | 1| ae2x + (a 1)ex 1 1 ae2x + (a 1)ex (2 + )ex
2 2 2
3a a a 6 + a
ex[aex + (a 1) (2 + )] = ex[aex 3 )],由 aex 3 = 0得 x = ln 0
2 2 2 2a
6 + a 6 + a
F (ln ) 0 ,所以,存在 x0 (0, ln ) ,使 F (x0 ) = 0 ,且可使 x (0, x0 ) , F (x) 0,
2a 2a
F(x)单调递减, x (0, x0 ) 时, F(x) F(0) = 0 ,舍去
综上: a [1,+ ) ····························· 17分
(注:本题方法不唯一,可以参照上述答案给分情况酌情给分)
19 解:(1)因为 a1 = 6, a2 = 4,所以 2a2 = a1 + a3或 2a3 = a1 + a2,所以 a3 = 2或 5,
···································· 2分
当 a3 = 2时, 2a4 = a2 + a3符合题意,当 a3 = 5时, 2a3 a2 + a4且 2a4 a2 + a3,不符合题意
所以 a3 = 2 ······························· 5分
(2)因为 a2 = a5 = a8 = 0,其余项均为正项,所以 2a3 = a4或 2a4 = a3
若 a4 = 2a3时,对于 a3 ,a4 ,a5,因为 a5 = 0, 2a5 a3 + a4且 2a4 a5 + a3,故舍去
1 1 1 1
所以 2a4 = a3即 a4 = a3,所以, 2a6 = a4 , a6 = a3,因为 a8 = 0,所以 a7 = a6 = a3,
2 4 2 8
1 1 a a 1
所以, a9 = a7 = a3,又 a3 0,所以
6 = 9 = ,所以 a3, a6 , a9成等比数列
2 16 a3 a6 4
···································· 10分
(3)由题意 am = as = at = 0,其余项为正项,不妨设3 m s t,则 p = t
a a 1 a a
又 2an+2 = an+1 + an或 2a = a + a ,所以
n+2 n+1 = 或 n+2 n+1n+1 n+2 n =1, · 10分
an+1 an 2 an+1 an
2a
又 ,可得 m 1
= am 2 1 1
am = 0 ,所以, am 1 am 2 = am 1, am+1 = am 1 = (am 1 am 2 )
2am+1 = am 1 2 2
a a a a a a a
m 4时, a a = m 1 m 2 = 3 2 4 3 m 1
am 2
m 1 m 2
a2 a1 a2 a1 a3 a2 am 2 am 3
6
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1
设这m 3个因式中恰有 i个因式的值为 ,有m 3 i个因式的值为 1,所以,
2
1
a i m 3 i
1 i 1 1
m 1 am 2 = ( ) 1 = ( ) , i N , am+1 = (am 1 am 2 ) = ( )
i+1, i m 3
2 2 2 2
1
所以, (am+1)max = , ·························· 13分
4
因为 am = as = at = 0,且不可能 s = m +1,故 s m + 2,同理, t s + 2
1 a
类似的, a = (a s 1
as 2 am+2 am+1 as 1 as 2
s+1 s 1 as 2 ),当 s m + 2, =
2 am+1 am am+1 am as 2 as 3
1
设等式右侧有恰有 j个因式的值为 ,有 s 2 j 个因式的值为 1,则
2
am+2 aa m+1
as 1 as 2 1 j s 2 j
s 1 as 2 = (am+1 am ) = ( ) 1 (am+1 am ),当 s = m + 2时等式
am+1 am as 2 as 3 2
1 1 1 j 1 j+1
也成立,所以, as+1 = (as 1 as 2 ) = ( ) = ( ) ,其中0 j s 2 m, j N ,
2 2 2 2
1
a = ( ) j+1
1 1 1
s+1 am+1 = ······················ ,15 分
2 4 4 16
1 1 1 1
同理 at+1 = ( )
k+1 as+1 = , 0 k t 2 s,k N ,当且仅当 i = j = k =1时取等.
2 4 16 64
1
综上: ap+1的最大值为 ························ 17分
64
7
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