Tài liệu ôn thi ñại học năm 2011 - 2012
ðỗ Ngọc Nam_THPT Trung Giã. Phone: 0949088998. Mail:
1
BÀI TẬP PHƯƠNG TRÌNH, BẤT PHƯƠNG TRÌNH, HỆ PHƯƠNG TRÌNH MŨ VÀ LOGARIT
Bài 1. ðưa về cùng cơ số
(
)
(
)
2
2 2
log 3 log 3 8 1 0
x x
− − + + =
.
(
)
(
)
2 1 1 1
3 10 6 4.10 5 10 6
x x x x x
+ + − −
− + = −
.
2
log 16 log 7 2
x
x
− =
.
2 3 4 20
log log log log
x x x x
+ + =
.
( )
( )
( )
1log2
2log
1
13log
2
3x
2
++=+−
+
xx .
( )
2
2
9 3
3
1 1
log 5 6 log log 3
2 2
x
x x x
−
− + = + −
.
( ) ( ) ( )
8
4 2
2
1 1
log 3 log 1 log 4
2 4
x x x
+ + − = .
(
)
(
)
2 2
2 2 2
log 3 2 log 7 12 3 log 3
x x x x+ + + + + = + .
54
4
2
log
2
2
1
≤−
− x
x
(
)
(
)
2 2
1 5 3 1
3 5
log log 1 log log 1
x x x x
+ + > + −
(
)
( )
2
2
4 4 4
log 1 log 1 log 2
x x x
− − − = −
( ) ( )
2 3
4 8
2
log 1 2 log 4 log 4
x x x
+ + = − + +
(
)
+ = +
log 6.5 25.20 log 25
x x
x
(
)
2
2 2
log log
x x
− =
2 0,5
31
log log 2 2
16
x
− ≤
(
)
2
log log 4 6 1
x
x
− ≤
3
2 3
log 1
1
x
x
−
<
−
(
)
(
)
(
)
3 9 27
2log 1 2log 4 1 3log 10 7 1
x x x
+ + + − + >
(
)
(
)
2 2
1 1
2 2
1
log 2 5 log 2 4 3 2
2
x x x x
+ + ≥ + + −
xxxx
5353
logloglog.log
+=
(
)
(
)
2 2
log 2 4 3 log 2 12
x x
x+ = − + +
(
)
(
)
(
)
2
3 3 9 3
log 1 2log 2 log 1 6 9 log 4
x x x x x
+ + + = − + + −
(
)
(
)
31log1log2
2
32
2
32
=−++++
−+
xxxx
( )
4 2
2 1
1 1
log 1 log 2
log 4 2
x
x x
+
− + = + +
(
)
2 4
log log 3 2
x x
− − >
(
)
(
)
2 2
2
1 log log 2 log 6
x x x
+ + + > −
(
)
(
)
9 1
3
2log 9 9 log 28 2.3
x x
x+ ≥ − −
2 3 3 1 5
6 2 .3
x x x
+ + +
=
2
5 25
log ( 4 13 5) log (3 1) 0
x x x
− + − − + >
2 2 2 3 4 2 4 2
2 16 2 4
3
log 1 log ( 1) log 1 log ( 1)
2
x x x x x x x x
+ + + − + = + + + − +
(
)
(
)
(
)
2
3 3 9 3
log 1 2log 2 log 1 6 9 log 4
x x x x x
+ + + = − + + −
.
(
)
(
)
2 2
2 5
2 2 5
log 2 11 log 2 12
x x x x
+
+
− − = − − . Đ/s :
2 2 5; 2 5
+ −
Bài 2. Logarit hóa, mũ hóa.
4 1 3 2
2 1
5 7
x x
+ +
=
2
5 .3 1
x x
=
2 1
1
5 .2 50
x
x
x
−
+
=
3 2
2 3
x x
=
(
)
(
)
2 3 5 7
log log log log
x x
≤
2
2x 3
x 2
x
3 .4 18
−
−
=
Bài 3. ðặt ẩn phụ
− − +
− + − + =
2 1 1 1
5.3 7.3 1 6.3 9 16
x x x x
16 64
log 2.log 2 log 2
x x x
=
2
5 5
5
log log 1
x
x
x
+ =
Tài liệu ôn thi ñại học năm 2011 - 2012
ðỗ Ngọc Nam_THPT Trung Giã. Phone: 0949088998. Mail:
2
( ) ( )
3
2
5 1 5 1 2 0
x x
x +
− + + − =
(
)
− − < −
2 2 2
2 2 4
log log 3 5 log 3
x x x
2.27 18 4.12 3.8
x x x x
+ = +
2 3
3
3
1
9 27 81
3
x
x x x
−
+
=
(
)
(
)
(
)
26 15 3 2 7 4 3 2 2 3 1
x x x
+ + + − − =
3
3 1
8 1
2 6 2 1
2 2
x x
x x−
− − − =
2 2
2
log .log (4 ) 12
x
x x
=
8
2
4 16
log 4
log
log 2 log 8
x
x
x x
=
(
)
(
)
1
2 2
log 4 4 .log 4 1 3
x x+
+ + <
(
)
2
25
log 125 .log 1
x
x x
=
2 2
5 1 5
4 12.2 8 0
x x x x− − − − −
− + =
( )
3 9
3
4
2 log log 3 1
1 log
x
x
x
− − >
−
2 2
2 1
3
log (4 4 1) log (2 7 3) 5
x
x
x x x x
+
+
+ + + + + =
(
)
(
)
7 3 5 7 3 5 14.2
x x
x
+ + − =
3
log 3 .log 1 0
x
x x
+ ≥
( )
2 4 2
1
2 log x 1 log x log 0
4
+ + =
2006
1 2
2 2
9 10.3 1 0
x x x x+ − + −
− + =
ðH-B-07 Giải phương trình:
(
)
(
)
2 1 2 1 2 2 0
x x
− + + − =
ðH-D-07 Giải phương trình:
2 2
1
log (4 15.2 27) log 0
4.2 3
x x
x
+ + + =
−
A-2006 Giải phương trình
3.8 4.12 18 2.27 0
x x x x
+ − − =
2 2
1 3
log log
2 2
2. 2
x x
x
≥
1 1
15.2 1 2 1 2
x x x
+ +
+ ≥ − +
D-2003 Giải PT:
2
2 2
2 2 3
x x x x
− + −
− =
2
2
3
27
16log 3log 0
x
x
x x
− >
(
)
(
)
2 1 2
1 1
2 2
log 4 4 log 2 3.2 .
x x+
+ < −
4 2
2. log 2 log 16 7 0
x x+ − =
(
)
(
)
2
2
2
log 4 log 2 5
x x
− >
1 2
1
5 log 1 logx x
+ >
− +
2
ln 1 ln ln 2
4 6 2.3 0
x x x+ +
− − =
2
2
1 2
2
log 4 log 8
8
x
x
+ <
(
)
2
4 2
log 2 2 6log 1 2 0
x x
+ − + + =
2 10 3 2 5 1 3 2
5 4.5 5
x x x x
− − − − + −
− <
(
)
3
log 2 log 2
x x
x x
≤
2
1 4
2
log log 2 0
x x
+ − >
2
2 2 2
log 2 log 6 log 4
4 2.3
x x
x
− =
2
2
log
2
2
x
x
≤
2 4
0,5 2 16
log 4log 4 log
x x x
+ ≤ −
( )
(
)
( )
2 2
3 2 2 2 3 2
3
2 1 log log 4 1 log log 4 2log log 2
x
x x
x x x x
x
+ − = + +
ðH-B-2006 Giải BPT
(
)
(
)
x x 2
5 5 5
log 4 144 4log 2 1 log 2 1
−
+ − < + +
Bài 4. Tính ñơn ñiệu của hàm số
(
)
2 3
log log 2
x x
= +
(
)
2
2 2
log 1 log 6 2
x x x x
+ − = −
(
)
25 2 3 5 2 7 0
x x
x x
− − + − =
(
)
2 3 2
.3 3 12 7 8 19 12
x x
x x x x x
+ − = − + − +
( ) ( ) ( ) ( )
2
3 3
3 log 2 4 2 log 2 16
x x x x
+ + + + + =
(
)
( )
2
log 6 4 log 2
x x x x
+ − − = + +
(
)
(
)
(
)
(
)
2 3
4 2 log 3 log 2 15 1
x x x x
− − + − = +
(
)
5 7
log log 2
x x
= +
Tài liệu ôn thi ñại học năm 2011 - 2012
ðỗ Ngọc Nam_THPT Trung Giã. Phone: 0949088998. Mail:
3
(
)
2 2
3 3
log 1 log 2
x x x x x
+ + − = −
(
)
2
7 2
log 1 log
x x x
+ + ≥
(
)
2 3
log 1 log
x x
+ >
2 2
4 2 4
log log log
64 3.2 3. 4
x x x
x
= + +
2
log
2
3 1
x
x
= −
)324(log)18(log39
33
+=+− xx
xx
(
)
1 2ln 1
x
e x x
+ = + +
3 3
log 1 log
4.15 5 0
x x
x
+
+ − =
. Đ/s : x = 1.
( )
2
2
2 1
2 6 1 log
2 1
x
x x
x
+
− + =
−
(
)
2 2
3log 2 9log 2
x x x
− > −
(
)
(
)
5 4
log 3 3 1 log 3 1
x x
+ + = +
2
3 3
(2 1)log (4 9)log 14 0
x x x x
+ − + + =
(
)
1 2
2
4 2 log 1 1
x x
x x x
+
− = + + − −
. ñặt t =
(
)
2
log 1
x
+
, tính ñơn ñiệu
Bài 5. Hệ phương trình
2 2
ln(1 ) ln(1 )
12 20 0.
x y x y
x xy y
+ − + = −
− + =
ðH-B-2005 Giải hệ
x y
log ( x ) log y .
2 3
9 3
1 2 1
3 9 3
− + − =
− =
2
3 1 2 3
3 1 1
2 2 3.2
x y y x
x xy x
+ − +
+ + = +
+ =
ðH-A-2004 Giải HPT:
log (y x) log
y
x y
1 4
4
2 2
1
1
25
− − =
+ =
−=−
+=+
−+
.yx
xyyx
xyx 1
22
22
. ð/s: (1;0);(-1;-1)
4 2
4 3 0
log log 0
x y
x y
− + =
− =
. ð/s: (1;1),(9;3)
( )
2
2
2
4 2 0
2log 2 log 0
x x y
x y
− + + =
− − =
. ð/s: (3;1)
2 2
2
2
2 log 2 .log 5
4 log 5
x x
x
y y
y
+ + =
+ =
(
)
4
4
4
4
3
8 6
x y
x y
x y
x y
−
−
+ =
+ =
2 2
2
2 2 2 1
2 2 2
4 2 4 4
2 3.2 112
x x y y
y x y
− + −
+ +
− + =
+ =
3 3
log ( ) log ( )
2 2
4 4 4
4 2 2
1
log (4 4 ) log log ( 3 )
2
xy xy
x y x x y
− =
+ = + + +
2
3
3
1 4
2 1 log 1
log 3
(1 log )(1 2 ) 2
x
x
y
x
y
y
−
+ − =
− + =
2 2
ln 2ln 6 ln 2 ln 6 ln ln
3 2 5
x y
x x x x x y
+ + − + + = −
+ =
2 2 2
3 3
3 3 27 9
( , )
log ( 1) log ( 1) 1
x y x y x y
x y
x y
+ + + +
+ = +
∈
+ + + =
ℝ
2 1
2 1
2 2 3 1
2 2 3 1
y
x
x x x
y y y
−
−
+ − + = +
+ − + = +
(
)
2
2
1
2
2 2
3
2 2
2
2 2 4 1 0
x
y
x
xy
x y x x y x
−
+ + =
+ − − + =
2
2
4 2
1
log 2log2 log 1
2 2
x y y
y
x
+ = + +
− = +
(
)
1
7
6 5log 6 5 1
x
x
−
= − +
2
3 1 2 3
3 1 1
2 2 3.2
x y y x
x xy x
+ − +
+ + = +
+ =
(
)
2
log 2 8 6
8 2 .3 2.3
x x y x y
y x
+
− + =
+ =
Tài liệu ôn thi ñại học năm 2011 - 2012
ðỗ Ngọc Nam_THPT Trung Giã. Phone: 0949088998. Mail:
4
{
( )
3
2
log 3
2 12 .3 81
x
x y
y y y
+ =
− + =
(
)
2
log 2 2 1 2
9.2 4.3 2 .3 36
x
x y x y
y xy
− − =
+ = +
(
)
(
)
3
3 27
log 2 1 log 3 2
x x
+ − = −
2 8
2 2 2 2
log 3log ( 2)
1 3
x y x y
x y x y
+ = − +
+ + − − =
( ) ( )
2 2
2
2
3 2
2010
2009
2010
3log 2 6 2log 2 1
y x
x
y
x y x y
−
+
=
+
+ + = + + +
)12(log1)13(log2
3
5
5
+=+− xx
(
)
(
)
ln ln ln ln
ln ln 1
2 3.4 4.2
x y
x y x y
e e y x xy
+
− = − +
− =
ðH-D-2006 CM với mỗi a>0 hệ sau có nghiệm duy nhất
ln(1 ) ln(1 )
x y
e e x y
y x a
− = + − +
− =
Chứng minh rằng hệ:
2
2
2009
1
2009
1
x
y
y
e
y
x
e
x
= −
−
= −
−
có ñúng 2 nghiệm x > 0; y > 0.
(
)
2 2 2
2 2 2 2
4 9.3 4 9 .7
4 4 4 4 2 2 4
x y x y y x
x
x y x
− − − +
+ = +
+ = + − +
. ð/s: (1; -1/2) pt thứ nhất thoát bằng hàm số.
Bài 6. Tích
− + + + + +
+ = +
2 2 2
3 2 6 5 2 3 7
4 4 4 1
x x x x x x
(
)
(
)
5 3
3
log 2 log 2log 2
x x x
− = −
(
)
= + −
2
9 3 3
2 log log .log 2 1 1
x x x
(
)
(
)
2
4 11 .2 8 3
0
log 2
x x
x x
x
+ − − −
≥
−
−+−>−+− xxxxx
2
1
log)2(22)144(log
2
1
2
2
2 2
2
2 4.2 2 4 0
x x x x x+ −
− − + =
(
)
2
4 2
log 8 log log 2 0
x
x x
+ ≥
4
2
1162
1
>
−
−+
−
x
x
x
(
)
2 1 2 2 2 1
3 2 2 3 2 2
x x x x
x x
− − − −
+ + > + +
(
)
(
)
1 2 1 2 2
2 5 11 2 24 1 9 2
x x x
x x x x
+ − −
+ + − < − − −
D – 2010:
3 3
2 2 2 2 4 4
4 2 4 2
x x x x x x
+ + + + + −
+ = +
3 2 3 4
2 1 2 1
.2 2 .2 2
x x
x x
x x
− + − +
+ −
+ = +
(
)
( )
2
2
4
1 1
log 3 4
log 2
x
x x
<
−
+ −
2 3 2 2
3 3 3 3
2 log 8 log 2 log 3 log 4
x x x x x x x
− + − ≥ − +
( ) ( )
2
2 7 7 2
log log 3 2log 3 log
2
x
x x x x x
+ + = + +
(
)
2 2 2
2
3 2 log 3 2 5 log 2
x
x x x x x− + ≤ − + −
(
)
( ) ( )
2 2
2
3 3 3
2log 4 3 log 2 log 2 4
x x x
− + + − − =
1
2
3 1
3
2
(9 2.3 3)log ( 1) log 27 .9 9
3
x
x x x
x
+
− − − + = −
( )
(
)
3
2
2
2 2 3
5 5
log 1
log
log log .log 1
log 2 log 2
x
x
x x x
+
+ − + >
(
)
2 2 2 2
2 2
2 34 log 34 15.2 4 2 1 log 2
x x x
x x x
+ +
+ + = + + +
( ) ( ) ( )
2
2 6 2 6
log .log 2 log 2log 2
2
x
x x x x x
+ + = + +
(
)
(
)
2 2
16 4 log 2 1 log 4 2
x x
x x
− + < +