职业高中一年级第二学期数学期末试卷含详解

1
A． AB OB OA
B． AB BA 0
C． AB OB OA
D． AB BC CD AB
18．演讲比赛中共有 9 位评委分别评出某选手的原始评分，评定该选手的成绩时，从 9 个原始评
分中，去掉 1 个最高分，1 个最低分得到 7 个有效评分，7 个有效评分与 9 个原始评分相比，
······················································································································· (A B) 7． x2 y2 Dx Ey F 0 是圆的一般方程··································································· (A B)
2．数列
1 1 2
，
1 23
，
1 3 4
，
1 45
……的通项公式是
an
1 n(n 1)
······································
(A
B)
3． a
b 的充要条件是
a
b
且
a
与
b
同向···································································· (A
20．已知向量 a (1, 3) ， b (1, 2) ，记 c a b ，则 a, c __________.
21．在等差数列an中，已知 a1 a2 a3 a4 a5 20 ，那么 a3 __________.
城北学校 2020——2021 学年第二学期期末考试
职一数学试卷
一、是非选择题：本大题共 10 小题，每小题 3 分，共 30 分，对每小题的命题作出正确的判断，对的
选 A，错的选 B。
1．an既是等差数列又是等比数列，则该数列前 n 项和为 na1··········································· (A B)
A．2:3
B．4:9
C． 2 : 3
D． 8 : 27
16．圆 x2 y2 2x 4 y 0 的圆心到直线 3x 4 y 5 0 的距离为·········································( )
A． 16 5
B．2
C． 2 5
D．0
17．下列命题中正确的是··················································································· ( )
B． 1 2
C． 1 3
D． 1 5
13．两个向量共线是两个向量相等的············································································ ( )
A．充分条件
B．充要条件
C．既不充分也不必要条件
D．必要条件
14．在空间四边形 ABCD 中，E、F 分别是 AB、CD 的中点 AD⊥BC，AD=BC，则 EF 和 BC 所成的角
A． a b 2c
B． b ab
C． a c 2b
D．a，b，c 成等比数列
12．若 x，a，2x，b 成等比数列，则 a:b=······································································ ( )
A． 3 5
8．直线 y 2x 1与 y 1 x 1 互相垂直······································································· (A B) 2
9．同时抛掷两枚一元硬币，两枚都出现正面的概率是 1 ·················································· (A B) 4
10．从 3，4，5，6，7，8，9 中任取一个数到的数是 3 的倍数的概率是 3 ··························· (A B) 7
二、选择题：本大题 8 小题，每小题 5 分，共 40 分。
11．若 lg a ， lg b ， lg c 三数成等差数列，则···································································( )
不变的数字特征是······················································································ ( )
A．中位数
B．平均数
C．方差
D．极差
三、填空题，本大题 6 小题，每小题 5 分，共 30 分
19．直线 y 2 x 2 与两坐标轴围成的三角形面积是__________. 3

B)
4．零向量没有方向···································································································(A B) 5．平行于同一直线的两个平面平行············································································· (A B) 6．若直线 m 在平面α内，直线 l 在平面β内，设甲：l∥α，乙：l∥m，则甲是乙的充分不必要条件
是··················································································································· ( )
A．45°
B．60°
C．30°
D．90°
15．如果两球的体积比为 8:27，那么这两个球的面积之比为············································· ( )