Bonsoir,
A = (3x - 4) (2x + 5) - (3x - 4) (7 - x)
A = (3x - 4) [2x + 5) - (7 - x)]
A = (3x - 4) (2x + 5 - 7 + x)
A = (3x - 4) (3x - 2)
B = (3x + 2) (2x + 3) + 3x + 2
B =2 (x + 2) (3x + 2)
C =(3x + 2)² - 100x²
C = (3x + 2 - 10x) (3x + 2 + 10x)
C = (- 7x + 2) (13x + 2)