Tìm x

Bài 7 Tìm x, biết:

a) (x – 2)(x – 3) + (x – 2) – 1 = 0

b) (x + 2)^2 – 2x(2x + 3) = (x + 1)^2

c) 6x^3 + x^2 = 2x