2.2X+2X+ X≤2⇔X2−2 =X2−4X+ 4 ⇔X=32XQ2= 1 X= 0X52−7.Q⇔D) 5.2X= 7√10X−2....
2
.2
x+
2
x+
x
≤
2
⇔
x
2
−
2 =
x
2
−
4x
+ 4
⇔
x
=
3
2
x
q
2
= 1
x
= 0
5
−
7.
q
d)
5.2
x
= 7
√
10
x
−
2.5
x
⇔
5.
2
5
x
+ 2 = 0
⇔
x
= 2
.
=
2
5
−
2 = 0
⇔
3
2
x
+
3
2
x
e)
27
x
+ 12
x
= 2.8
x
⇔
3
2
3x
= 1
⇔
x
= 0.
2
x
=
2
3
−
2
3
x
−
2 = 0
⇔
3
f)
3.8
x
+ 4.12
x
−
18
x
−
2.27
x
= 0
⇔
3.
2
3
3x
+ 4.
2
3
2x
=
−1
⇔
x
= 1.
Bài tập 5.24.
Giải các bất phương trình sau
a)
27
x
+ 12
x
<
2.8
x
.
b)
25
2x−x
2
+1
+ 9
2x−x
2
+1
≥
34.15
2x−x
2
.
9
x
−
3
x+1
+ 2
>
3
x
−
9.
c)
9
x
1
−
13.6
x
1
−1
+ 4
1
x
<
0.
d)
√
e)
5
2x
−5
4−5
x+1
x
+6
≤
1.
f)
5
2x+1
4−7.5
−12.5
x
x
+4
≤
2
3
.
Lời giải.
−
2
<
0
⇔
3
2
x
a)
27
x
+ 12
x
<
2.8
x
⇔
3
2
3x
<
1
⇔
x <
0.
0
≤
x
≤
2
"
2x−x
2
2x
−
x
2
≥
0
≥
1
−
34.
5
3
2x−x
2
+ 9
≥
0
⇔
b) PT
⇔
25.
25
9
2x−x
2
x
≥
1 +
√
.
2x
−
x
2
≤ −2
⇔
≤
25
9
x
≤
1
−
√
x >
1
−
13
6
.
3
2
1
x
<
3
2
⇔ −1
<
x
1
<
1
⇔
c)
9
x
1
−
13.6
x
1
−1
+ 4
1
x
<
0
⇔
9
4
1
x
+ 1
<
0
⇔
2
3
<
3
2
x
1
x <
−1
.
x <
2
3
x
−
9
<
0
0
≤
x
≤
log
3
2
0
≤
x
≤
log
3
2
9
x
−
3.3
x
+ 2
≥
0
d) BPT
⇔
3
x
−
9
≥
0
x
≥
2
x
≥
2
.
x >
log
3
79
15
9
x
−
3.3
x
+ 2
>
9
x
−
18.3
x
+ 81
5
x
≤ −3
−
√
7
5
x
<
2
x <
log
5
2
e)
4
−
5
x
−3 +
√
7
≤
5
x
<
2
x >
log
5
3
.
5
x
>
3
⇔
5
2x
−
5.5
x
+ 6
≤
0
⇔
5
2x
−
5
x+1
+ 6
≤
1
⇔
−5
2x
−
6.5
x
−
2
5
x
>
3
5
x
≤ −
1
2
log
5
2
5
< x <
log
5
4
5
f)
4
−
7.5
x
5
<
5
x
≤
4
5
x >
log
5
2
.
5
2x+1
−
12.5
x
+ 4
≤
2
3
⇔
−10.5
2x
+ 3.5
x
+ 4