Bonjour,
Factorisation de la forme : a(x - x₁)(x - x₂)
2x² + 8x - 10 = 0
Δ = b² - 4ac = 8² - 4 × 2 × (-10) = 144 > 0
x₁ = (-b -√Δ)/2a = (-8 - 12)/4 = -20/4 = -5
x₂ = (-b + √Δ)/2 = (-8 + 12)/4 = 4/4 = 1
Donc ∀x, f(x) = 2(x + 5)(x - 1)
Vérification : 2(x + 5)(x - 1) = 2(x² - x + 5x -5) = 2(x² + 4x -5) = 2x² + 8x - 10
⇒ Donc pas d'erreurs
