Tìm x: (x + 1)(x - 1)^2 - (x + 1)(x - 2)^2=0

a) (x+1)(x-1)^2-(x+1)(x-2)^2=0
b) (3x+1)(x-3)^=(3x+1)(2x-5)^2
c) ((x+5)(3x+2)^2=x^2(x+5)