1) (3-5x)(x-2) = 0
3-5x = 0 hay x-2 = 0
5x = 3 hay x = 2
x = 3/5 hay x = 2
Vậy S = {3/5 ; 2 }
2) (7-28x)(x-2017) = 0
7-28x = 0 hay x-2017 = 0
28x = 7 hay x = 2017
x = 1/4 hay x = 2017
Vậy S = {1/4 ; 2017}
3) (4x-10)(x^2 + 4) = 0
4x-10 = 0 hay x^2 + 4 = 0
4x = 10 hay x^2 = -4
x = 5/2 hay x^2 = -4 (loại vì x^2 $\geq$ 0)
Vậy S = {5/2}