Bonjour !
Exercice 13 :
A = 1 - x² = (1-x)(1+x)
B = (9x-5)² - 16x² = (9x-5)² - (4x)² = (9x-5-4x)(9x-5+4x)
= (5x-5)(13x-5) = 5(x-1)(13x-5)
C = (5y+8)² - 25 = (5y+8)² - 5² = (5y+8-5)(5y+8+5)
= (5y+3)(5y+13)
D = -16a² + 25 = 5² - (4a)² = (5-4a)(5+4a)
E = 1 + 4x² + 4x = (2x)² + 2×2x×1 + 1² = (2x+1)²
F = 25 + 36t² + 30t = (6t)² + 2×6t×5 + 5² = (6t+5)²
Exercice 14 :
a. 49x² - 9 = (7x+3)(7x-3)
b. x² + 10x + 25 = (x+5)²
c. 9x² - 42x + 49 = (3x-7)²
d. x² - 16x + 64 = (x-8)²
N'hésite pas si tu as une question :)
