Question

х^3 - 3x^2 - 4x + 12 =0

Answer 1

x^2(x - 3) - 4(x - 3) = 0 
(x^2 - 4) (x - 3) = 0 
(x - 2) ( x + 2) (x - 3) = 0 
x = 2
x = - 2 
x = 3