Répondre :
(3a + 4b)² = (3a)² + 2 x 3a x 4b + (4b)² =9a² + 24ab + 16b²
(4X - 1/3)² = (4X)² - 2 x 4X * 1/3 + (1/3)² = 16X² - X x (8/3) + 1/9
(4X - 1/3)² = (4X)² - 2 x 4X * 1/3 + (1/3)² = 16X² - X x (8/3) + 1/9