Répondre :
Bonsoir,
(12x+7)² - (11-5x)(12x+7) = (144x² + 168x + 49) - (132x + 77 - 60x² - 35x)
(12x+7)² - (11-5x)(12x+7) = 144x² + 168x + 49 - 132x - 77 + 60x² + 35x
(12x+7)² - (11-5x)(12x+7) = 204x² + 71x - 28
(12x+7)² - (11-5x)(12x+7) = (144x² + 168x + 49) - (132x + 77 - 60x² - 35x)
(12x+7)² - (11-5x)(12x+7) = 144x² + 168x + 49 - 132x - 77 + 60x² + 35x
(12x+7)² - (11-5x)(12x+7) = 204x² + 71x - 28