Bonsoir ,
(a + b)² = a² + 2ab + b²
(a - b)² = a² - 2ab + b²
(a + b)(a - b)² = a² - b²
Donc on a :
(x + 8)² = x² + 16x + 64
(3x - 9)² = 9x² - 54x + 81
(x + 7)(x - 7) = x² - 49
