1 và N > 0
log a N
a
0
a
1
N
và
( a > 0, a
*a>1
:
*0
1)
0
y
y
O
0
a>1
à
à
x
1
x
1
O
y=logax
y=loga x
garit:
ln x '
ln u '
1
x
u'
u
và
ln x '
và
ln u '
1
x
u'
u
à
hà
log a x '
log a u '
a/ y
log 1
2
2
x 1
0
x 1
x 1
0
x 1
1;
log 1 log 5
5
và
và
log a u '
log a x '
1
x ln a
u'
u.ln a
à
à
x 1
.
x 5
log 1
b/ y
u'
u.ln a
1
x ln a
x2 1
.
x 3
x
x
x
x
1
1
1
1
0
1
x 1
1 0
x 1
x
1 x 1
2
0 x
x 1
x
1 x 1
1
x2 1
x 3
log 1 log 5
3
x2
2
x 1
1
x 3
x2 1
0
5
x 3
2
x 1
1
x 3
x2 1
5
x 3
0 log 5
0
3
x
x
1 x 2
3 2 x 7
x 2
0
x 3
x 2 5 x 14
0
x 3
x
3
0
x
3; 2
2; 7
Bài 2. Tính giá
a.
31
log3 4
5
1
2 .3 log5 2
3
7 log7 4
3
4
72 7 log7 9
2 log 7 6
4 4 19
b.
1
c. 72 49 2
1
72 49 2
log7 9 log7 6
log7 9 log7 6
5
5
log
log
5
4
3
4
5
2 log 5 4
72
9
36
1
16
d.
-GA-RÍT
Bài 1
a. A log 9 15 log 9 18 log 9 10
18 4,5
22,5
A
log 9 15 log 9 18 log 9 10
3
1
log 1 400 3log 1 3 45
2
3
3
2 log 1 6
3
1
log 1 3
2
6
log 36 2
1
log 3 3 3
2
log 9 3 3
3
2
36.45
20
log 1
3
log 1 9 2
log 3 3 4
4
3
1
log 1 3
2
6
c. C log 36 2
C
15.18
10
1
log 1 400 3log 1 3 45
2
3
3
b. B 2 log 1 6
B
log 9
1
1
log 6 2
log 6 3
2
2
1
log 6 2.3
2
1
2
d. D log 1 log 3 4.log 2 3
4
D log 1 log 3 4.log 2 3
log 4 log 2 3.log 3 4
1
log 2 2
2
log 4 log 2 4
4
1
2
Bài 2. Hãy tính
a. A log 2 2 sin
A log 2 2 sin
b. B log 4
B
log 4
3
3
7
log 2 cos
12
3
7
3
log 2 cos
12
3
3
3
log 2 2 sin
12
3
49
3
21
49
3
21
3
log 4
log 4
12
3
12
.cos
log 2 sin
12
log10 tan 4 log10 cot 4
d. D log 4 x
D
9
log tan 4.cot 4
log 4
3
7
log1 0
1
log 4 216 2 log 4 10 4 log 4 3
3
1
log 4 216 2log 4 10 4log 4 3
3
1
6.34
log 4 63 log 4 10 2 log 4 34 log 4 2
3
10
6
1
2
1
9
c. C log10 tan 4 log10 cot 4
C
log 2
log 4 x
x
35
50
3
3
3
49
3
21
3
9
log 4 7 3
1
Bài 3. Hãy tính :
a. A log a a 3 a 5 a
A log a a 3 a 5 a
log a a
3
1 1
2 5
1
2
3
1
5
37
10
1
27
10
b. B log a a 3 a2 5 a a
1
1
log a a 3 a 2 5 a a
B
c. log 1
a
1
log a
4
a a
a
3
1
3
1
3
3
10
a 5 a3 3 a 2
a4 a
a 5 a3 3 a2
log 1
log a a
1 1
2
2 5
a
a
3 2
5 3
1 1
2 4
34
15
3
4
91
60
d. log tan10 log tan 20 log tan 30 .... log tan 890
log tan10 log tan 20
( vì : tan 890 cot10
log tan 30 .... log tan 890
tan10 tan 89 0
log tan10 tan 890.tan 20.tan 87 0...tan 450
tan10 cot10 1
0
)
e. A log 3 2.log 4 3.log 5 4......log15 14.log16 15
A
log 3 2.log 4 3.log 5 4......log 15 14.log16 15 log16 15.log15 14....log5 4.log4 3.log3 2
f. A
A
1
log 2 x
1
log 2 x
log x 2011!
Bài 4
1
log 3 x
1
log 3 x
1
1
..........
log 4 x
log 2011 x
1
1
..........
log 4 x
log 2011 x
x
log16 2
1
4
2011!
logx 2 logx 3 ... logx 2011 logx 1.2.3...2011
log 2011! 2011!
1
a 2 b2
a.
c2; a
a2
2
1
log c b a
0, c 0, c b 1 , thì :
log c b a log c b a 2 log c b a.log c b a
0, b
c2 b2
1
log c b a
c b c b
2
2 log c b a.log c b a
log a c b
log a c b
log c b a log c b a
1
log a N
log c N
log a N log b N
a, b, c 1
log b N log c N
b2
1
log b N
log b N log c N
log c N .log b N
2 log N b log N a log N c
log a N log b N
log a N .log b N
1
log a N
log a N
log c N
ac
1
1
log c N log b N
log a N log b N
log b N log c N
log x a, log y b, log z c
log b y
2 log a x.log c z
0
log a x log c z
x, y, z , a, b, c 1
log x a, log y b, log z c
1
log a x
1
log c z
log x a log z c 2log y b
2
log b y
log b y
2 log a x.log c z
log a x log c z
a2 b2
a 2 b2
2 ln
a b
3
7 ab
a b
ln a ln b
ln
2
9ab
a b
3
a b
3
ln a ln b
2
7 ab
2
ab .
e
log ax bx
log ax bx
f
log a b log a x
1 log a x
log a bx
log a ax
log a b log a x
1 log a x
ln
VP
dpcm
hai
a b
3
ln a ln b
2
1
log a x
1
1
.........
log a 2 x
log a k x
VT= log x a log x a 2 ...log x a k
k k 1
2 log a x
1 2 3 ... k log x a
k 1 k
2 log a x
VP
Bài 1. Tính
a. A log 6 16
A
log12 27
log 6 16
x
log 3 27
log 3 12
log 3 2 4
log 3 6
4 log 3 2
1 log 3 2
log 2 5
a; log 2 3 b
log12 27
A log 6 16
b. C log 3 135
log 3 135 log 3 5.33
C
c. D log 6 35
x
log 3 5 3
log 27 5
a; log 8 7
3
1 log 3 4
x
log 2 5
3
log 2 3
b; log 2 3
log 3 4
a
3
b
3
1
x
3 x
3 x
(*)
log 3 2
x
2x
2 3 x .2 x 12 4 x
x x 3
x 3
a 3b
b
c
1
1
log 3 5 log 3 5 3a; b log 8 7
log 2 7 log 2 7 3b (*)
3
3
log 2 5.7 log 2 5 log 2 7 log 2 3.log 3 5 log 2 7 b.3a 3b
log 6 35
log 2 2.3
1 log 2 3
1 log 2 3
1 b
Ta có : a log 27 5
Suy ra : D
d. Tính : log 49 32
Ta có : log 2 14 a
log 2 14
1 log 2 7
5
log 49 32
log 2 2
log 2 7 2
5
2 log 2 7
a
a
log 2 7
a 1
5
2 a 1
Bài 2
a. A
A
log a b log b a 2 log a b log ab b log b a 1
log a b log b a 2 log a b log ab b log b a 1
log a b 1
log a b
2
1 log ab a
1
3b a 1
b 1
2
log a b 1
log a a
log a b 1
1
1
log a b
log a ab
log a b
log a b 1
1
1
log b a
log a b
log a b
b. B log 2 2 x 2
log 2 2 x 2
B
1 3log 2 x
c. C
C
log 2 x x
log 2 x x
log 2 x
2
1
1
1 log a b
1
2
log a b
1 log a b
1
log 22 x 4 1 2 log 2 x log 2 x log 2 x 1
2
2
9 log 2 x
3log 2 x 1
log x log 2 x 1
2
log a p log p a 2 log a p log ap p
log a p log p a 2 log a p log ap p
log a p 1
log 2a p
log a p
1 log a p
log a b 1
log a b
1
4 log 2 x
2
log a p
log a p 1
2
a
log p
2
log a p
log a p
1 log a p
log a p
log a b 3; log a c
a. x a 3b 2 c
Ta có : log a x log a a 3b 2 c
c. x
3 2 log a b
1
log a c 3 2.3 1 8
2
a4 3 b
c3
4
1
log a c 3log a c
3
4
1
3
2
6 10
a 2 4 bc 2
3
ab 4 c
Ta có :
log a x
23
a4 3 b
c3
a 2 4 bc 2
log a
2
Bài 4
3
3
4
ab
4
4
c
log a p
3
log a p
log a x
Ta có : log a x log a
2
log a p
Bài 3
b. x
1
1
log 22 x 4
2
log x log 2 x 1
8 log 2 x
2
2
1
log a b 2log a c
4
1
161
12 1
3
12
1
4log a b
3
1
log a c
2
2
3
28
3
2
:
a. log a 3b
1
log a log b
2
log 2
a
0; a 2 9b 2 10ab
3b
2 log a 3b
log 2a
b
c
log 2a
a
c
b
0; a 2 9b 2
3b
a 2 6ab 9b 2
2 log 2 log a log b
;
10ab
4ab
a 3b
log a 3b
log 2
log a b.log b c.log c a 1
c
a
b
log 2a ; log 2b ; log 2c
b b
c c
a a
log 2a
log a
b
c
b
c
log 2a
c
a
b
log log 2b log 2c
b
c c
a a
2
a
b
c
b
log a
* log a b.log b c.log c a 1
c
.
b
1
c
b
log a
log a b.log b a
log 3 4
log a
log 3 3 1; log 4
3log6 1,1
3log6 1 1; 7 log6 0,99
7 log6 1 1
c
b
2
1
log 4
1
3
. Ta có :
1
1
log 4 4 1 log 3 4 log 4
3
3
log6 1,1
log6 0,99
3
7
. Ta có :
log 3 4
a/ log 0,4 2 log 0,2 0,34 .
b
c
log a a 1
b
c
a
log a .log b log c
b c
c a
a b
Bài 1
log a2
3 log6 1,1
7 log6 0,99
2
log a2
c
b
2
4ab
1
log a log b
2
2 1
Ta có :
b/ log 5
3
log 0,4 2
0,3 1
3
4
log 3
4
2
.
5
log5
c/ 2log 3 3
5
3
1
4
0
3
1, 0
4
0
1
2
log 5
3
2
1
5
3
4
log 5 1 0
3
2
5
log 3
4
log 3
4
log 3 1 0
2
5
log 5
3
3
4
4
.
2 log
log 5 3 log 5 1
Ta có :
log 0,2 0,3 log 0,4 2
log 0,2 0,3 log 0,2 1 0
5
1
3
Ta có :
log 0,4 1 0
1
log 5
2
log 5 1
3
5
3
log5
2 log
51
1
2
3
log 5 1
20 1
3
0
log 5 3 log 5
1
1
2
d/ log 3 2 log 2 3 .
Ta có :
log 3 1 log 3 2 log 3 3
0 log 3 2 1
log 2 2 log 2 3 log 2 4
1 log 2 3 2
log 2 3 log 3 2
e/ log 2 3 log 3 11 .
Ta có :
1 log 2 3 2
log 3 11 log 3 9
2
log 3 11 log 2 3
2log 2 5 log 1 9
f/ 2
8.
2
Ta có : 2 log 2 5 log 1 9 log 2 25 log 2 9 log 2
2
2
25
9
g/ 4
log2 3 log4
Ta có : 4
5
11
25
92
625
81
648
81
2log 2 5 log 1 9
25
9
2
2
2
log 2
25
9
2log 2 5 log 1 9
8
2
8
2
18 .
log 2 3 log 4
5
11
81.11
5
2
2log 2 3
891
5
1
5
log 2
2
11
90
5
2
log 2 9 log 2
18
4
5
11
2
log 2
log 2 3 log4
5
11
9 11
5
9 11
5
18
81.11
5
25
9
log 3 2 log 1
h/ 9
9
8
9
5.
log 3 2 log 1
Ta có : 9
k/
9
log6 2
1
6
1
log
2
6
3
2 log 3 2 log 9
8
9
3
log 3 2 log 3
8
9
log 3
2.3
3
6
8
8
36
8
3
1
log
2
18 .
6
5
6
log6 2 log6 5
6
log6 10
6
log6
1
10
1
10
3
1
1000
Bài 2. Hãy so sánh :
a/ log 2 10 log 5 30 .
Ta có :
log 2 10 log 2 8 3
log 2 10 log 5 30
log 5 30 log 5 36 3
b/ log 3 5 log 7 4 .
Ta có :
log 3 5 log 3 3 1
log 7 4 log 7 7 1
log 3 5 log 7 4
1
e
c/ 2 ln e3 8 ln .
2 ln e3
Ta có :
1
8 ln
e
2.3 6
8 ln
8 1 9
1
e
2 ln e3
Bài 3
a/ log 1 3 log 3
2
1
2
2.
1
Ta có : log 1 3
log 3
2
log 3
40
8
5
log6 2
1
Ta có :
6
8
9
1
2
0
1
2
log 3
log 3
1
2
1
2
1
1
log 3
2
1
2
1
log 3
2
2
*
log 3
1
2
1
1
log 3
2
2
3
18
5
b/ 4log 7 7log 4 .
5
5
Ta có : 4log 7
log5 7
7log7 4
5
7log5 7.log 7 4
7log5 4
c/ log 3 7 log 7 3 2 .
Ta có : log 3 7 0
d/ 3log
2
5
1
log 3 7
5log5 3
2
1
log 3
2
log 2 5
5log 2 5.log 5 3
5log2 3
log19 log 2 .
1
log 3 log 10 log 3 log 3 10
2
Ta có :
19
361
log19 log 2 log
log
2
4
log 900
f/ log
5
361
4
log
7
5
log 900
1
log 3 log19 log 2
2
log 5 log 7
.
2
2
Ta có :
2
5 log2 3 .
Ta có : 3log 5
e/
log 3 7 log 7 3 log 3 7
7
5. 7
2
log
5
7
2
log 5. 7
log 5 log 7
2
Bài 4. Hãy so sánh :
a. log 3
6
5
log 3
5
6
6
5
Ta có :
5
log 3
6
log 3
b. log 1 9 log 1 17
3
3
5
5
6
log 3
6
log 3
0
0
6
log 3
5
5
log 3
6
6 5
5 6
3 1
log 3
6
5
log 3
5
6
1
1
Ta có :
3
9 17
0
log 1 9 log 1 17
3
3
c. log 1 e log 1
2
2
1
1
2
0
Ta có :
log 1 e
e
log 1
2
2
-GA-RÍT
Bài 1
x2 2x 2 ex
a. y
x2
y
2 x 2 ex
s inx-cosx e 2 x
c. y
y
2 x 2 ex
x2 2 x 2 ex
y'
cosx+sinx e 2 x
ex
ex
ex
ex
e
e
e
e
y
x
y'
x
ex
e
x
ex
e
e
x
ex e
x
x 2
y'
2x
x
2
1
ln x
x
ln x
x
3sin x c osx e 2 x
x
ln x 2 1
e. y
2 s inx-cosx e 2 x
x
d. y ln x 2 1
y
x2 e x
s inx-cosx e 2 x
b. y
y
y'
y'
1 1
.x ln x
x2 x
1 ln x
x2
e
x
ex e
x
4
e
x
e
x 2
f. y
1 ln x ln x
y
1 ln x ln x
ln x 1 ln x
x
x
y'
1 2 ln x
x
Bài 2
:
a. y x 2 ln
y
2
x ln
x2 1
x
2
1
y ' 2 x.ln
x
2
x2 x
2 x2 1
1
2
2 x.ln
x
1
x3
2 x2 1
b. log 2 x 2 x 1
y
log 2 x 2
c. y
y
3
3
x 1
ln 2 x
y'
x 4
x 4
log 2
log
y'
2
3
'
1
3
2
ln x
3
1
x
2
3 x 3 ln x
1
ln 2
16
x 4
2
:
x 4
x 4
16
x 4 ln 2
2
x2 9
x 5
x2 9
x 5
log 3
1
f. y log
y
ln x
x 4
x 4
e. y log 3
y
2
ln 2 x
d. y log 2
y
2x 1
x x 1 ln 2
y'
y'
2
1 2x x 5 x
2
ln 3
x 5
9 x2 9
:
x 5
x 2 10 x 9
x 5 x 2 9 ln 3
x
2 x
1
x
2 x
y'
x 1 1
1
x
:
ln10 16 x x 2 x
x 1
8 x ln10 1
x
Bài 1
a. lim
x 0
lim
x
ln 3 x 1
ln 2 x 1
x
ln 3 x 1
ln 2 x 1
x
0
b. lim
x 0
x
ln 3 x 1
3x
lim
x 0
sin 2 x
2x
2x
ln 3 x 1
0
sin 2 x
c. lim
x 0
lim
x
lim
x
e.
0
e5 x
x
3
0
4x
0
4
2x
3
e3
3
lim e 5
x
0
e5 x 1
2. 5 x
5e 3
2
ex 1
x 1 1
ex 1
x 1 1
a. lim
x 0
ln 4 x 1
e3
2x
lim
x
lim 4
x
0
lim
x
x
0
e5 x
3
2
ln 4 x 1
ln 4 x 1
d. lim
x 0
x
sin 2 x
3x
ln 2 x 1
tan x
ex 1
0
x
lim
x
x 1 1
1.2
ln 2 x 1
0
2
x
2
lim
ln 3 x 1
lim
x
ln 3 x 1
0
3
x
3
lim
2
3 2 1
2x
ln 2 x 1
lim
x 0
tan x
b. lim
x 0
lim
x
e2 x
0
c. lim
x 0
e2 x
lim
x
0
ln 2 x 1
2x
tan x
x
x
2
e3 x
5x
e3 x
5x
e2 x 1
e3 x 1
lim 3
0 5
x 0
5 3x
.2 x
2
lim
x
2 3
5 5
1
5
e3 x 1
x
e3 x 1
e3 x 1
lim 3
3
0
x 0
x
3x
lim
x
d. lim xe
x
1
x
x
1
lim xe
1
x
x
e. lim
x 0
lim
x
0
lim
x
0
lim x e
x
1
ex 1
lim
x
1
x
sin 3 x
x
sin 3 x
x
f. lim
x 0
x
1
x
lim 3
x
0
sin 3 x
3x
3
1 cos5x
x2
1 cos5x
x2
5x
2
lim
2
x 0
4 5x
25 2
Bài 3.
a. lim
x 0
cosx cos3x
sin 2 x
2 sin 2
25
2
1
cosx cos3 x
lim
x 0
sin 2 x
lim
x
2
lim
x
2
sin 2 x
0
x
2
2 sin 2
x
t
2
tan
t
t
2 sin cos
2
2
c. xlim x 2 sin
2
t
.
2
1
cosx
t
Khi x
cos
;t
2
0
2
2
t
2
lim
x
x
1
x
t
;t
1
sin t
t
1
t anx
cosx
lim
t
0
2
t
1 cost
sint
cot t
tan
t
2
t
2
0
3
x 2
x
sin x
4
1
2
3t
t
lim x 2 sin
6t 3
x
3
x
lim 6t 3
t
0
4
x
4
tan
2 2 cos x
d. lim
x
1
t anx=
3
x
3
lim x 2 sin
x
x
lim
4
1
t anx .
cosx
t
x
4 cos x.sin 2 x
lim
x 0
sin 2 x
x
1
t anx
cosx
b. lim
x
2 sin 2 x sin
2 2 cos x
sin x
x
4
x
4
sin x
2 2 cos x
sin x
4
4
;t
0
2 2 cos
2
lim
o
t
2
2
t
2 1 cost+sint
sint
4
t
t
t
2 sin cos
2
2
2
t
t
2 sin cos
2
2
2 tan
4
sin t
2 sin 2
t
4
;x
2 2 cos x
4
2 1 cost+sint
sint
lim
t
t
2
sin
2
t
t
cos
2
2
t
cos
2
2 tan
t
2
2
3