PHƯƠNG TRÌNH, BẤT PHƯƠNG TRÌNH VÀ HỆ PHƯƠNG TRÌNH
x+ x − x+ =x + 2. 1 2 2
2 −x −x = − x
2 1
cos sin
m m
x
+
+ = + với m n, là các số nguyên dương
x
+
− =
7.
2
2
2
x y z x x y z
y z x y y z x
z x y z z x y
8.
4
6 2
cos 2x
x− x x + x+ − x − x = x + x− +
12.
1 2z 8
3
4 0
x xy y
x y xy x yz
x y z
x y z
−
< <
13.
2
1
x
14. 3
2005−x + 2006−x =1
16cos x +3 =2048cosx−768 17. 3 2x+ + =1 1 x3 +3x2 +2x
7 37 1
19.
3 3
82
16x −16x −20x +20x +5x +2x−7=0
11x −14x+9 + 11x −2x+3+ 17x +2x+3 = 2 2x +4
4
2x −11x+ 21 3− 4x−4 =0 24. 2
25.
2
2
2
26.
2
x y xy
Trang 22
35 12 1
x
x
x
−
29. 2
2
2
2
97 36 0
0
x y
x
y
<
>
31.
1 1
1 1
1 1
y x
x z y
y x z
z
+
2007
x
x x
2
x
2
9
9
35
8
=
36.
2
1 1
x e y
− +
=
+
1
x
>
3x 2+ 9x +3 + 4x+2 1+x+ x +1 =0
2
x
0
y x
2cos 3x+6cosx+1 =162cosx−27 44. 2
2x− +1 x −3x+ =1 0
2x+3+ x+ =1 3x +2 2x +5x+3 16−
3 15
2
Trang 32
1
2
2
9 3
y xy
55 4x +(x−12 2) x +11−x=0 56
4
57. tan 2
x
2 2
π π
−
−
− − − >
58
2 3
2 3
2 3
2 30 16
4 4 44 1 1
2cos x+2 3 sin cosx x + =1 3 sinx + 3 cosx
2
x
x
+
68. 3
70. 2log7t=log3(2+t) 71. cos 6x −cos 4x=4 1 cos3( + x)
72.
4x −x+10 +2x=3 2x −x + 9x −4x+4
76
8
16
2
xy
+
77
4
4
2 1
2 4
2 1
1 4
x y x
x y
x y y
x y
+
+
78
3
xy x y
x
y
4 x + x+ = +1 1 5x +4x −2x − x 81 3 x+6+ x− =1 x2 −1