[email protected] , ответ добавлен 30.03.2018 в 09:01

X^3 - 3x^2 - 4x + 12 = 0
x^2 (x - 3) - 4(x - 3) = 0
(x - 3)(x^2 - 4) = 0
(x - 3)(x - 2)(x + 2) = 0

x - 3 = 0
x1 = 3

x - 2 = 0
x2 = 2 

x + 2 = 0 
x3 = -  2

 0