Réponse :
a) (x + 6)² = (a + b)² = a² + 2ab + b²
= x² + (2 * x * 6) + 6²
= x² + 12x + 36
d) (6 - 2x)² = (a - b)² = a² - 2ab + b²
= 6² - (2 * 6 * 2x) + (2x)²
= 36 - 24x + 4x²
b) (x - 3)² = (a - b)² = a² - 2ab + b²
= x² - (2 * x * 3) + 3²
= x² - 6x + 9
e) (5 + 9x)(5 - 9x) = (a + b)(a - b) = a² - b²
= 5² - (9x)²
= 25 - 81x²
c) (4 + 8x)² = (a + b)² = a² + 2ab + b²
= 4² + 2 * 4 * 8x + (8x)²
= 16 + 64 + 64x²
f) (1 + 3x)(1 - 3x) = (a + b)(a - b) = a² - b²
= 1² - (3x)²
= 1 - 9x²
Bon courage ^-^