Решите уравнение:x^3-x^2-3x+2=0

Question

Решите уравнение:
x^3-x^2-3x+2=0

Answer 1

X^3 - x^2 - 3x + 2 = 0;
 (x^3 - x^2 - 2 x) - (x - 2) = 0;
x (x^2 - x - 2) - (x-2) = 0;
x(x-2)(x+1) - (x-2) = 0;
(x-2)(x(x+1) - 1) = 0;
(x-2)(x^2 + x - 1) = 0;
x - 2 = 0; ⇒ x = 2;
x^2 + x - 1 = 0;
D = 1+4 = 5;
 x = (-1+sgrt5) / 2;
 x = (-1- sgrt5) / 2.