A) 3 4− X(25 2− X)=8X2+ −X 300 (1) − − + = − + (2) X X X5 10 7 4B) 2 1 3( ) 2 3 3 2( 1)X+ − X− = X+ − (3) C) 5 2 8 1 4 2 56 3 5X XD) 3 2 3 1 2 5+ − + = X+ (4) 2 6 3GIẢI A) ( )1 ⇔ −3 100X+8X2 =8X2+ −X 300 ⇔ −100X− = −X 300 3− ⇔ −101X= −303⇔ =X 3VẬY....
50. Giải phương trình:a) 3 4− x
(
25 2− x)
=8x2
+ −x 300 (1) − − + = − + (2) x x x5 10 7 4b) 2 1 3( )
2 3 3 2(
1)
x
+
−
x
−
=
x
+
−
(3) c)5
2
8
1
4
2
5
6
3
5
x
x
d)3
2
3
1
2
5
+
−
+
=
x
+
(4)2
6
3
Giải a)( )
1 ⇔ −3 100x+8x2
=8x2
+ −x 300 ⇔ −100x− = −x 300 3− ⇔ −101x= −303⇔ =x 3Vậy S ={ }
3b)( )
2 ⇔8 1 3(
− x) (
−2 2 3+ x)
=140 15 2−(
x+1)
⇔ −8 24x− −4 6x=140 30− x− ⇔15 0x=121vô nghiệm Vậy S = ∅c)( )
3 ⇔5 5(
x+ −2)
10 8(
x− =1) (
6 4x+ −2)
150⇔
+
−
+
=
+
−
x
x
x
25
10
80
10
24
12 150
⇔ −
= −
⇔ =
79
158
2
Vậy S ={ }
2d)( )
4 ⇔3 3(
x+ −2) (
3x+ =1)
12x+10⇔
+ −
− =
+
⇔
= − ⇔ = −
9
6
3
1 12
10
6
5
5
x
x
x
x
x
6
Vậy 5 S= − 6