(x + 2)(x + 4) = 8
x² + 6x + 8 = 8
x² + 6x = 0
x(x + 6) = 0⇒x = 0 ou x + 6 = 0 ⇒x = - 6
2) (4x - 12) - (x - 3)² = 0
4(x - 3) - (x - 3)² = 0
(x - 3)(4 - (x - 3)) = 0
(x - 3)(4 - x + 3) = 0
(x - 3)(7 - x ) = 0
x - 3 = 0 ⇒ x = 3 ou 7 - x = 0 ⇒x = 7
3) x³ = 4x ⇔ x³ - 4x = 0
x(x² - 4) = 0 ⇒ x = 0 ou x² - 4 = 0
(x - 2)(x + 2) = 0 ⇒ x = 2 ; x = - 2
L'équation possède 3 solutions
x = 0
x = 2
x = - 2