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高雄市明誠中學 高一數學平時測驗 日期:104.12.22.
範
圍 3-3 對數函數(A) 班級 一年____班 姓 座號 名
一、填充題(每題 10 分)
1. (1)(log 9 log 3)(log 16 log 4)2 8 3 9 ________.
(2) 3 3 3 1 3 3
log 54 log 4.5 log log 81
27 3 ________.
答案: (1)35
3 (2)1 6
解析: (1)原式 2 2 2 3 3
2
log 3
(log 3 )(log 16 log 2) log 8
2 2 3
(2 log 3 1log 3)(log 32)
3
5
2 3
( log 3) (log 2 )7
3
2 3
( log 3)(5 log 2)7
3
2 3
35 35 35
(log 3)(log 2) 1
3 3 3
(2)原式 3
3
54 4.5 1 log 27 3
3 3
3 3
9 log 3
3 3 3
3
log 3
3 3
3 5 6
log 3 3
log 33 16 1
6 2. 化簡下列各式:
(1)( )1 1 log0.54 2
________.
(2)log(log 10 )10 ________.
(3)31 log 4 3 ________.
答案: (1)8 (2)1 (3)12 解析: (1)原式 12 12
log 2 log 4
( )1 2
1 log 812
( ) 8
2 (2)原式
1
10 1
log(log10 ) log 1
10
(3)原式 log 3 log 43 3 log 123
3 3 12
1
3. 試求下列各值:
(1)若log3x ,則 x4 ________.
(2)若log10 1
y3,則y________.
(3)若 log 9z ,則2 z________.
2
(4)若log 6 1
a 2,則 a________.
(5)若log 2b ,則 b8 ________.
(6)若logc 43 ,則 c2 ________.
答案: (1)81 (2)310 (3)3 (4) 1
36 (5)16 (6)83 解析: (1)34 x 81
(2)
1 3 3
10 10 y (3)z2 9 z 3 (4)
1
2 1 1
6 36
a a a 36 (5)b 28 24 16
(6)c2 43 c 8 3
4. 化簡:(1)log 49 log 813 7 ________.(2)log 9 log 625 log 164 3 5 ________.
答案: (1)8 (2)16
解析: (1)原式log 73 2log 817 2 log 7 log 813 7 2 log 813 2 4 8
(2)原式log 3 log 52 3 4log 165 log 3 (4 log 5) log 162 3 5 4 log 5 log 162 5 4 log 162
4 4 16 5. (1) log 5 log 23 3
3 ________.
(2)8log 72 ________.
(3)3log34 ________.
(4)0.1log 310 ________.
答案: (1)10 (2) 1
343 (3)16 (4)1 3 解析: (1)原式3log 103 10
(2)原式 2 3log 72 2log 72 3 7 3 1 343
(3)原式3log 163 16 (4)原式 0.1
log 1
3 1
0.1 3
6. 若alog 2, log 45 b 50 ,則a b ab
________.
答案: 1 2
解析: a b 1 1 ab b a
log 50 log 54 2 log 50 log 254 4 log4 50
25 log 24 1
2 7. 解:52 log 35 3x4,則 x______.
答案: 5 3
解析: 5log 95 9 3x4 5
3 5
x x 3
8. 設 a,b,c 為正整數,若alog5202blog5205clog52013 ,則 a b c3 _________。
答案: 15
3
解析: alog5202blog5205clog52013 3
log5202a log5205b log52013c3
log5202a 5 13b c 35203 2a 5 13b c
(2 5 13)3 32 5 139 3 3 2 5 13a b c 得a9 ,b3 ,c3,故 a b c =9+3+3=15
9. 6 2 6
2
log 18 (log 3)
log 6
________.
答案: 1
解析: 原式 6 2 6 6
2
log 3 log 6 (log 3)
log 6
2
6 6 6
(log 3) (log 3 1) log 2
2
6 6 6 6
(log 3) (log 3)(log 2) log 2
6 6 6 6
(log 3)[log 3 log 2] log 2
6 6 6
(log 3) (log 6) log 2
log 3 log 26 6 log 66 1
10. 化簡: 5 6
1log 4
log 3 2
25 6 ________.
答案: 9 2 解析: 原式
1 6 2
25 log 4
log 9
25 6
9 6log 26 9 6log6 2 9 2
11. 試求下列各值:
(1)log41 log5 1 log61 log7 1 log8 1 log9 1
3 4 5 6 7 8________.
(2)log 9 log 125 log 84 3 5 ________.
答案: (1)1
2 (2)9
解析: (2)原式(log 8 )(log 7 )(log 6 )(log 5 )(log 4 )(log 3 )9 1 8 1 7 1 6 1 5 1 4 1
9 8 7 6 5 4
( log 8)( log 7)( log 6)( log 5)( log 4)( log 3)
9 8 7 6 5 4
log 8 log 7 log 6 log 5 log 4 log 3
log 39 1
2 (3)原式log 3 log 5 log 24 2 3 3 5 3
4 3 5
(2 log 3)(3log 5)(3log 2)
4 3 5
18(log 3 log 5 log 2)
18 log 24 18 1
2 9 12. log 2 log 50 log 5 log 20 log 4 ________.
答案: 1
解析: 原式log 2 (log 5 log10) log 5(log 2 log10) 2 log 2 log 2 log 5 log 2 log 5 log 2 log 5 2 log 2
log 5 log 2
(log 5 log 2) log10 1. 13. 化簡:log3 3 7 6 log3 3 7 ______. 6
答案: 3 2
解析: 原式log3 (3 76)(3 76) log3 63 36 log 273 12 1log 273
2 3
2
4
14. 化簡: 3 12 3 1
logaa loga loga a loga
a a
______.
答案: 1 6
解析: 原式
1 1
3 2 3
1 6
2 1
log ( ) log
a a a a a aa 6
15. 化簡: 1 1 5 1
2
(log 2)[(log 1) (log 2) ] 4
______.
答案: 1 2
解析: 原式 1
5
(log 2)[2 1 ] log 2
2
(log 2)(1 log 5)
2
2 2
(log 2) (log 2 log 5)
(log 2) (log2 10)
log 10 1
2
17. 若log 26 a, log 76 ,試以 a, b 表示b log11242 ______.
答案: 1 4
b a b
解析: 112 6 6
6 6
log 42 log (6 7) log 42
log 112 log (16 7)
6 6
4
6 6
log 6 log 7 1 log 2 log 7 4
b a b
18. 若log 32 ,試以 a 表示(1)a log 12962 __________ (2)log2 27
4 __________
(3)1log 5 log3 3 5
2 2 __________ (4)3x 45,x __________.
答案: (1) 4 4a (2) 3a (3)2 1
a (4)10 a
解析: (1)log 12962 log (22 43 )4 log 22 4log 32 4 4 4 log 32 4 4a (2)log2 27 log 27 log 42 2 log 32 3 2 3log 3 22
4 3a 2
(3)1 3 3 5 3 3 5 3 5
log 5 log log 5 log log
2 2 2 5
2
3
2
1 1
log 2
log 3 a
(4)xlog 43 5 5 log 43 5 log 23 2 10 log 23
2
1 10
10log 3 a