文档内容
2024 年高考诊断性测试
数学参考答案及评分标准
一、选择题
A C B C B D A A
二、选择题
9.ABD 10.BCD 11.BC
三、填空题
5 9 5
12.4 13.10, 10+ 14.[ , ]
2 4 2
四、解答题
2
15.解:(1) f'(x)=2ax+1− , ··································· 2分
x
1
直线x+2y+1=0的斜率k =− ,
2
由题意知 f'(2)=2, ··································· 4分
1
即4a+1−1=2,所以a= . ···································· 5分
2
(2) f(x)的定义域为(0,+). ··································· 6分
1
因为 f(x)0,所以b− x2 −x+2lnx.
2
1
设g(x)=− x2 −x+2lnx,x(0,+),则b g(x) . ························ 8分
2 max
2 −x2 −x+2 (−x+1)(x+2)
g'(x)=−x−1+ = = ··················· 9分
x x x
当x(0,1)时,g'(x)0,所以g(x)在(0,1)单调递增,
当x(1,+)时,g'(x)0,所以g(x)在(1,+)单调递减, ··············· 11分
3
所以g(x) = g(1)=− .
max 2
3
所以b− . ······························· 13分
2
16.解:(1)因为AB⊥ AC,AB= 3AC =3,
1
所以ACB=60 ,OA= BC = 3. ············································ 1分
2
因为AB=3,AD=2DB,所以DB=1.
在 DBO中,DBO=30 ,DB=1,OB = 3,
由余弦定理OD2 =12 +( 3)2 −21 3cos30 =1,所以OD=1. ········· 3分
在 ADO中,OD=1,AD=2,AO= 3,由勾股定理,AO⊥OD. ····· 4分
因为AO⊥平面ABC,OD平面ABC,
1
所以AO ⊥OD. ····················································· 5分
1
数学参考答案(第 1 页,共 4 页)
{#{QQABSYKEogCoAAAAAQgCEwEoCkGQkAGCAKoOAAAIMAAAyQFABCA=}#}因为AO AO=O,所以OD⊥平面AOA. ······································ 6分
1 1
因为AA 平面AOA,所以AA ⊥OD; ····································· 7分
1 1 1
(2)由(1)可知,OA,OD,OA 两两垂直,以O为坐标原点,OA,OD,OA 方向分别为x,y,z
1 1
轴正方向,建立如图所示的空间直角坐标系O−xyz. ······ 8分
因为AA =2 3,AO= 3,所以AO=3. ············· 9分
1 1
3 3
则A( 3,0,0), A(0,0,3),B(− , ,0). ··········· 10分
1 2 2
3 3 3 3 3
可得BA =( ,− ,3),BA=( ,− ,0),
1 2 2 2 2
设m =(x,y,z)为平面ABA 的一个法向量,
1
3 3
x− y+3z =0
2 2
则 ,取x= 3,则y =3,z =1,
3 3 3
x− y =0
2 2
故m =( 3,3,1), ····························· 12分
由题意可知,n=(0,1,0)为平面AOA的一个法向量, ······················· 13分
1
m n 3 3 13
因为cosm,n= = = ,
|m||n| 13 13
3 13
所以二面角B− AA −O的余弦值为 . ······························· 15分
1 13
17.解:(1)两人得分之和大于100分可分为甲得40分、乙得70分,甲得70分、乙得40
分,甲得70分、乙得70分三种情况,所以得分大于100分的概率
1 1 2 1 4 1 1 1 4 1 2 1 7
p= + + = . ·························· 4分
5 3 3 2 5 3 3 2 5 3 3 2 45
1 5 1 1 1
(2)抢答环节任意一题甲得15分的概率 p= + = . ············ 7分
2 12 2 4 3
(3)X 的可能取值为2,3,4,5.
1 2
因为甲任意一题得15分的概率为 ,所以任意一题乙得15分的概率为 . ····· 8分
3 3
1 1 1 2 1 4
P(X =2)=( )2 = , P(X =3)=C1 = ,
3 9 2 3 3 3 27
1 2 1 2 28
P(X =4)=C1 ( )2 +( )4 = ,
3 3 3 3 3 81
1 2 1 2 1 2 32
P(X =5)=C1 ( )3 +C3( )3 = . ··················· 12分
4 3 3 3 4 3 3 3 81
所以X 的分布列为
X 2 3 4 5
1 4 28 32
P
9 27 81 81
·································· 13分
数学参考答案(第 2 页,共 4 页)
{#{QQABSYKEogCoAAAAAQgCEwEoCkGQkAGCAKoOAAAIMAAAyQFABCA=}#}1 4 28 32 326
所以E(X)=2 +3 +4 +5 = . ····················· 15分
9 27 81 81 81
c
18.解:(1)由题意知,a =2, = 5, 又因为c2 =a2 +b2, ··················· 2分
a
解得b=4.
x2 y2
所以,双曲线C的方程为 − =1. ············································· 3分
4 16
设直线l的方程为x=my+3,
x2 y2
− =1
联立 4 16 ,消x可得,(4m2 −1)y2 +24my+20=0. ··············· 4分
x =my+3
不妨设P(x ,y ),Q(x ,y ),
1 1 2 2
1 −24m 20
则m ,且y + y = ,y y = . ························· 5分
2 1 2 4m2 −1 1 2 4m2 −1
y y y y
所以k k = 1 2 = 1 2 ····················· 7分
AP AQ x +2 x +2 m2y y +5m(y + y )+25
1 2 1 2 1 2
4
=− . ····························· 9分
5
1
(2)设直线AP的方程为y =k(x+2),则直线DM :y =− (x−3),
k
y =k(x+2)
5k
联立 1 ,解得y = , ····································· 11分
y =− (x−3) M k2 +1
k
4 −100k
用− 替换上式中的k 可得y = . ······························· 13分
5k N 25k2 +16
25 3125k2
故S S = | y y |= ································· 15分
1 2 4 M N (k2 +1)(25k2 +16)
3125
= .
16
25k2 + +41
k2
16 16 2 5
因为25k2 + 2 25k2 =40,当且仅当k = 时,“=”成立,
k2 k2 5
3125 3125
所以S S , 故S S 的最大值为 . ························· 17分
1 2 81 1 2 81
19.解:(1)由题意可得y=1−cost,|OB|= BM =t ,
所以x=|OB|−sint =t−sint, ································ 2分
数学参考答案(第 3 页,共 4 页)
{#{QQABSYKEogCoAAAAAQgCEwEoCkGQkAGCAKoOAAAIMAAAyQFABCA=}#}所以x=t−sint ,y=1−cost. ································ 4分
(2)证明:由复合函数求导公式y= yx,
t x t
yx y sint
所以y = x t = t = . ·········································· 7分
x x x 1−cost
t t
sint
所以tan= ,
1−cost
2cos2 2
因为1+cos2=2cos2= =
sin2+cos2 tan2+1
2 2(1−cost)2
= = =1−cost = y ,
sint 2−2cost 0
( )2 +1
1−cost
1+cos2
所以 为定值1. ········································· 10分
y
0
t
(3)由题意,F(t)= (1−cost)2 +sin2t = 2−2cost =2|sin |. ·········· 13分
2
t t
因为0 ,sin 0
2 2
t
所以F(t)=2sin ,
2
t
所以F(t)=−4cos +c(c为常数), ······································ 15分
2
F(2)−F(0)=(−4cos+c)−(−4cos0+c)=8,
所以OE的长度为8. ································· 17分
数学参考答案(第 4 页,共 4 页)
{#{QQABSYKEogCoAAAAAQgCEwEoCkGQkAGCAKoOAAAIMAAAyQFABCA=}#}