高雄市明誠㆗㈻ 高㆒數㈻平時測驗 ㈰期:92.03.10 範 班級
圍 1-3 對數函數+Ans
座號
姓
㈴
㆒. 單㆒選擇題 (每題 10 分)
1、( D )
+ +
−− + 10 + 10 ) = 4
( 1 log ) 10 2 ( log
2
10 x 10 x 2xx
10x
2×
2
(A) (B)
4 log101
⋅
x
(C)1 (D)2log102 (E)2x
+102x 解解析析::
) 10 4 10
( 1 log ) 10 2 ( log 2
2 x +
10+
−x−
10+
x+
2x) 4 10 1 10
1 10 4 10 (4 log ) 10 4 10
(1
) 10 2 ( log 10
2 2 2 10
2 2
10 + +
+
× +
= × +
+
= + −
x x
x x
x x
x x
2 log 2 4
log10 = 10
=
( )
2、( D ) 10loglog2+log3 =? (A)5 (B)6 (C)log5 (D) log (E) log6 2⋅log3 解析解析::10log10
(
log6)
=(log6)log1010 =log63、( C ) x, y 皆為正數,若
x
3 =y
2, 2x 3
=y
,則以下何者正確? (A)x = 3
(B)x
=y
(C)x
x =y
y (D)4x
x =9y
y (E)9x
y =4y
x解析解析::
x
3 =y
2 9x3∴∴
x
3x =y
2xx
2∴∴
x
3x =y
3y= 0
∴∴
x
x =y
y 9x
3 =9y
2 =(3y
)2 =(2x
)2∴∴ =4 ∴∴
x
(不(不合合))或或 9 4, ,27
8
y
3
= 2
y x
= ,故,故x ≠
)3 log 2 2 log 2 27( 3 8 log 2 log 9
log 9
log
x
y = +y x
= + −) 3 log 3 2 log 3 9( 2 4 log 2 log 4
log 4
log
y
x = +x y
= + −∴∴log9
x
y ≠log4y
x,,故故9x
y ≠4y
x。 。 4、( A ) log3=
) 9 log(log
3
? (A)log9 (B)3log2 (C)3log3 (D)9 (E)27 解析解析:: log3=
) 9 log(log
3
3log log93( )
= og 9 l5、( B ) 設 ,則 之值為 (A)12 (B)27 (C)9
(D) (E)
3 2 log , 5
log3 =
a
b =5 3
log (log 2)
9 3 + b
9a +
b
3 log53 +
b
3 3
log5 +(logb 2)
2
9log b
解析解析::log35=
a
∴∴3a =5, , 9a =(3a)2 =25 logb2=3 ∴∴b
3 =2 故故0 27
2 25 9a + b3 = + =
6、( D ) x, y 為異於 1 的正實數,k 為實數,下列何者是錯誤的? (A)
(B) (C) (D) log
(E)
1 logx =
k
310 =3log
y x
xy
10 1010 log log
log = +
x
y
y
x
log10 = log10k k
2 1010 2log
log = 10
k
解析解析::∵∵log10(−2)2 ≠2log10(−2) ∴∴log10
k
2 ≠2log10k
3
log k10 若有若有意意義義⇒ k3 >0 ∴∴
k > 0
故成故成立立7、( E ) 設
x
=log35,則32x + 3−x之值為 (A)5 (B)9 (C) 3 28 (D)5 51 (E)
5 126
解析解析::
x
=log35 ∴∴3x =5⇒32x =25, ,5
3−x = 1 故故
5 126 5 25 1 3
32x + −x = + =
㆓. 多重選擇題 (每題 10 分)
1、(
BE
) 下列哪些式子是正確的? (A) (B)(C) (D)
) log77= 3
( log 2 ) 3 (
log7 − 2 = 7 − log
3 log6 6
1 4
3
log81 = log6(3+4)= + 4 (E)log 6 7 =log67 解
解析析::log7(−3)2 =2log7(−3)⇒真真數數要要大大於於0 0
4 log 3 log 4 3 log 4 log 3 log ) 4 3 (
log6 + = 6 + 6 ⇒ 6 ⋅ = 6 + 6
⇒
=log 7 7
log 6 6 上上下下可可同同時時平平方方或或開開根根號號
㆔. 填充題 (每題 10 分)
1、設 log (log 25) 1
2 ) 1 (log
log3 5
x
+ 3 2 = ,則x =
_____。答案答案::
2 2
解解析析::
log
3(log
5x ) + log
3(log
225 ) = 1
∴
∴log3(log5
x
⋅log225)=1 ∴∴ 3 2 log25 log 5 log
log
x
⋅ =2 2log
log
x
= 3 ∴∴2
22 2
3
=
= x
2、設log2=u
, log3=v
,試用u, v
表達下列算式(1) =
8
log75 ______。(2)log3 0.135 =______。(3)log524=______。
答
答案案::((11))
2 + v 5 − u
(2(2))3 2 31 −
− u
v
((33))u
v u
− + 1 3
解析解析::((11)) = 8
log75 log3×52 −3log2=log3+2log5−3log2=
v
+2(1−u
)−3u
=2+v
−5u
(2(2))log3 0.135=
3 2 3 ] 1
3 3 ) 1 3[(
] 1 3 3 log 3 5 3[log 1 1000
3 log5 3
1 × 3 = + − = − + − = − −
u v v
u
(3(3))log524=
u v u
−
= +
× 1 3 5 log
3 2 log
33、設31x =100, 310y =10,則 − =
y x
1
2 ______。
答案答案::−−11
解析解析:: x y
2 1
10 310 , 10
31= = ∴∴ 1
1 2
10
−−y
=
10
x ∴∴2−1 =−1y
x
4、(1) 2 −log224+2log23 2 = 8
log 27 3
1 ______。
(2)
(log
25 + log
4125 )(log
52 − log
254 ) =
______。答案答案::((11)) 3
−10 ((22)) 2 5
解析解析::((11))
( )
3 ) 10 8 2
1 2 ( 1 log 24 2
1 8
log 27
32 2
3 2
23
× × = × × = −
(2(2))
2 2 5 log 5 2 log ] 5 2 2 log 2 2 log 2 1 ][ 1 5 2 log
5 3
2 5 5 2 52
+ − = × =
[log
5、(1)
log
3427 =
______。(2)log
8( 4 + 2 3 − 4 − 2 3 ) =
______。答案答案::((11)) 4 3 (2(2))
3 1
解析解析::((11))
log
3427 =
4 3 3 log 4
3
3 =
(2(2))
log
8( 4 + 2 3 − 4 − 2 3 ) =
3 2 1 log ) 1 3 1 3 (
log8 + − + = 8 = 7、設
a = log
23
, ,則以 a, b 表示(1)b
=log37 =7
log6 24 ______。
(2)log32+log 3 22 +log33 23 +"+log83 28 =______。
答案答案::((11))
1 3
+
− +
a ab a
(2(2))a
204解析解析::((11))
a
2 1log3 = ,, = 7 log6 24
1 3 1 1
1 3
2 log 1
7 log 2 log 3 1 6 log
7 log 24
3 3 3
3 3
+
−
= + +
− + + =
−
= +
a ab a
a a b
(2(2))
a 2 204 log 204 2 log 8 1 2 8
log 3 1 2 3 log 2 1 2 2
log
3+
3+
3+ " +
3=
3=
8、(1)設 2
6
logx 1 =− ,則
x =
_____。(2)化a
2 1 2log5 = − 為
x
a =5,則x =
_____。答案答案::((11))± 6 (2(2)) 2 25
解析解析::((11)) 2 6
logx1 =− ∴∴
6
2 =1
x
− ∴∴x
=± 6 ((− 6不合不合)) (2(2))a
2 1 2log5 = − ∴∴1 2 log 2
− 5
a
= ∴∴2 log 25
1
5
=
a
∴∴ log 5
2
= 25
a
∴∴ ) 52
(25 a = ∴∴ 2
= 25
x
9、設
a, b, c 為異於 1 的正數,且 a
2 =b
3,b
2 =c
3,則(1)logab
=______。又 (2)loga5⋅log25c
=______。答案答案::((11)) 3 2 (2(2))
9 2
解析解析::((11))
a
2 =b
3 ∴∴ 32
a b =
∴∴3 log 2
log 3
2
=
=
a
b
aa
(2(2))loga5⋅log25
c
=9 log 2 3 2 3 2 2 log 1
2 log 1 2
1
322
3
= × × =
= b b
c
ba b
10、設
a
=log37, ,則b
=log38 log2849=______(以a, b 表示之)。
答案答案::
a b
a
3 26 + 解
解析析::log38=
b
∴∴ 2 3 log3b
= ∴∴
a b
a b a
a
3 2
6 3)
( 2
2 7
2 log
7 49 log
log 2
3 2 3
28 = +
+
⋅
= ⋅
= × 11、(1)
log
366
36 =
______ , (2)log50.2=______。答案答案::((11)) 3
2 (2(2))--11
解析解析::((11))
3 2 2 3 4 6 log 3
4
62 = = (2(2)) 1
5 log5 1=−
12、解方程式(1)logx25=2,則
x =
_____。 (2)log0.25x
=−3,則x =
_____。答案答案::((11))55 (2(2)) 6644 解
解析析::((11))
x
2 =25 ∴∴x = ± 5
((-5-5不合不合)) (2(2))(0.25)−3 =x
∴∴x
=43 =64 13、求(1)3log94 =______。(2)4
21log25+ 9
−2log3 5=
______。(3)3log9
(
log25)
×3log9(
log510)
=______。答案答案::((11)) 22 ((22)) 25
126 ((33))
2
解析解析::((11))3 4 42 2
1 3 log 4
log9 = 9 = =
( (22))
25 126 25 5 1 5)
(1 5
9
42log 5 2log 5 log 4 log 9
1
2 3 2 3
= +
= +
= + −
(3(3))3log9
(
log25⋅log510)
=3
log92= 2
log93= 2
15、(1)log25⋅log257⋅log498=______。(2)
= 27 log
3 log
2
4 ______。
(3)log810⋅log1012⋅log1214⋅log1416=______。
答案答案::((11)) 4 3 (2(2))
6 1 (3(3))
3 4
解
解析析::((11))
4 3 7 log 2
2 log 3 5 log 2
7 log 2 log
5
log × × = (2(2))
6 1 3 log 3
2 log 2 log 2
3
log × =
( (33))
3 4 2 log 3
2 log 4 14 log
16 log 12 log
14 log 10 log
12 log 8 log
10
log × × × = =
16、化簡log315⋅log515−log53−log35=______。
答案答案::22
解析解析::(1+log35)(1+log53)−log53−log35=1+log35log53=2
17、(1)化簡 + )+log 5=
5 (6 log 2 4) (5
log3 3 3 ______。
(2)化簡(log25+log0.250.2)(log252+log0.28)=______。
答案答案::((11)) 22 ((22)) 4
−15
解析解析::((11)) ) 5 log 9 2
5 (6 4 log 5 5 5 log log 6 4 2
log3 5+ 3 + 3 = 3 × 2× = 3 =
(
(22))
log 2 )
1 2 3 2 log ( 1 ) 5 2 log 5 1 (log ) 2 log 2 (log 5 )
log 1 5
(log
3 2 2 5 55 5 1
4 1
2
+ ×
2+ = + × −
4 2 15 log 2) ( 5 5 2log 3
5
2 × − =−
=
18、設正數 a, b, x, y 均不為 1,若loga
x
+logby
=2, logxa
+logyb
=−2,則=
+ 2
2 (log )
)
(loga
x
by
A
a
x
=log logb
y
______。
4 log81
x
= 1 答案答案::66解
解析析::令令 , , =
B
∴∴A
+ B=2,, 1 + 1 =−2B
A
故故AB
=−1A
2 + B2 =6㆕. 計算與證明題 (每題 10 分) 1、求解下列方程式:
(1) (2) logx25=2 (3) log0.2
x
=−2 (4)4 3 1 logx = 答案答案::((11)) 81 3
4
log 1 4
1
81
x
= ⇒x
= =(2(2)) logx25=2⇒
x
2 =25=52⇒ x = 5
((33)) ) 5 25
5 (1 ) 2 . 0 ( 2
log0.2
x
=− ⇒x
= −2 = −2 = 2 = ((44)) 3
4 3 1
log 4
1
=
⇒
=
x
x ⇒ x =( 3)4 =9
2、設
3 log16
=
a
,4 log81
=
b
,試以a, b 表示(1)
log2=?, log3=? (2)log854=? 答案答案::a
=4log2−log3,,b
=4log3−2log2( (11))
14 2 4
log
a
+b
= ,,
7 3 2
log
a
+b
=
(
(22))log854=
b a
b a b
a
b a b a
3 12
13 10 14 )
( 4 3
7 ) ( 2 3 14 ) ( 4
2 log 3
3 log 3 2 log
+
= +
× + + + + + =
3、設
f
(x
)=logx+3(x
2 −1)有意義,則x 的範圍為何?
答案答案::
f
(x
)=logx+3(x
2 −1)有有意意義義 ∴∴x
2 −1>0且且x + 3 > 0
且且x + 3 ≠ 1
∴
∴
− 3 < x < − 1
或或x > 1
且且x ≠ − 2
∴∴− 3 < x < − 2
或或− 2 < x < − 1
或或x > 1
4、設log102=u
, log103=v
,試用u 與 表達出下列各式: v
(1) log1075 (2) ) 81 (1
log10 (3) log100.48 (4) )
36 ( 9
log10 3 (5)
log
10( 18 × 9 )
答案答案::(1(1)) log1075=log10(3×52)=log103+2log105
) 2 log 10 (log 2 3 2 log
log 10 2 3
log10 + 10 = 10 + 10 − 10
= =
v
+2(1−u
)(2(2)) ) log 3 4log 3 4
v
81(1
log10 = 10 −4 =− 10 =− (3(3)) 10 10 log1048 log10102
100 log 48 48 . 0
log = = − =log1024⋅3−2
2
4 2
3 log 2 log
4 10 + 10 −
=
= u + v −
(4(4)) 10 103
10 3 ) log 9 log 36
36 ( 9
log = −
6 3log 3 2
log10 2 − 10
= (log 2 log 3)
3 3 2 log
2 10 − 10 + 10
=
v u v v u
3 2 3 ) 4 3(
2 −2 + = −
= (
(55))
log
10( 18 × 9 ) = log
1018 + log
109
2 10 2
102 3 log 3
2log
1 ⋅ +
= (log 2 2log 3) 2log 3
2 1
10 10
10 + +
= (
u
2v
) 2v
2
1 + +
=
v
u
3 21 +=