a) (5x3 - 3x2) : x2 = 7
5x3 : x2 - 3x2 : x2 = 7
5x - 3 = 7
5x = 7 + 3
5x = 10
x = 10 : 5
x = 2
Vậy x = 2
b) (12x3 - 8x) : x - 4x(3x - 1) = 0
12x3 : x - 8x : x - 12x2 + 4x = 0
12x2 - 8 - 12x2 + 4x = 0
-8 + 4x = 0
4x = 0 + 8
4x = 8
x = 8 : 2
x = 4
Vậy x = 4