a) 11 - 3(2x - 1) = -8x + 5
⇔ 11 - 6x + 3 = -8x + 5
⇔ -6x + 8x = 5 - 11 - 3
⇔ 2x = -9
⇔ x = -9/2
Vậy S = {-9/2}
b) (x - 3)/5 + (1 + 2x)/3 = 6
⇔ 3(x - 3) + 5(1 + 2x) = 6.15
⇔ 3x - 9 + 5 + 10x = 90
⇔ 13x = 90 + 9 - 5
⇔ 13x = 94
⇔ x = 94/13
Vậy S = {94/13}