Répondre :
(3 x 2x + 3 x 5) - (2x x 3x - 2x x 5 + 4 x 3x - 4 x 5)
= (6x + 15) - (6x² - 10x + 12x - 20)
= 6x + 15 - 6x² + 10x - 12x + 20
= 6x² + 4x + 35
= (6x + 15) - (6x² - 10x + 12x - 20)
= 6x + 15 - 6x² + 10x - 12x + 20
= 6x² + 4x + 35