Coucou
C = (5x - 2) (9x - 4) - (7x + 4) (5x - 2)
= (5x - 2) [ (9x - 4) - (7x + 4) ]
= (5x - 2) (9x - 4 - 7x - 4)
= (5x - 2) (2x - 8)
= 2 (x - 4) (5x - 2)
B 4x (x + 5) + (x + 5) (3x - 11)
= (x + 5) [ 4x + (3x - 11) ]
= (x + 5) (4x + 3x - 11)
= (x + 5) (7x - 11)
F = -28x + 49 + 4x²
= 4x² - 28x + 49 identité remarquable du type (a - b)² = a² - 2ab + b²
= (2x)² - 2 * 2x * 7 + 7²
= (2x - 7)²
Voilà j'espère avoir pu t'aider^^
