Question

Решите уравнение! плиииз!
х^3+2х^2-5х-6=0

Answer 1

x^3 + 2x^2 - 5x - 6 = 0 
x^3 + x^2 + x^2 + x - 6x - 6 = 0
(x^3 + x^2) + (x^2 + x) - (6x + 6) = 0
x^2(x + 1) + x(x + 1) - 6(x + 1) =  0
(x + 1)(x^2 + x - 6) =  0

1) x + 1 =  0
x₁ = - 1;

2) x^2 + x - 6 = 0
D = 1 + 24 = 25 = 5²
x₂ = ( - 1  +5)/2 = 2;
x₃ = ( - 1 - 5)/2 = - 3;

Ответ
- 3; - 1; 2