resolution dans R de lexpression 2 x³ + x² - 5x +2

Résolution dans R :

2x³ + x² - 5x + 2 = 0
2x³ - 2x² + 3x² - 3x - 2x - 2 = 0
(2x³ - 2x²) + (3x² - 3x) - (2x + 2) = 0
2x²(x - 1) + 3x(x - 1) - 2(x - 1) = 0
(x - 1)(2x² + 3x - 2) = 0
(x - 1)(x + 2)(2x - 1) = 0

x - 1 = 0
x = 1

x + 2 = 0
x = - 2

2x - 1 = 0
2x = 1
x = 1/2

S= {- 2 ; 1/2 ; 1}