Bonjour
i. (4x + 1)² - 25
= (4x + 1 + 5) (4x + 1 - 5)
= (4x + 6) (4x - 4)
= 8 (x - 1) (2x + 3)
j. (9x + 1)² - (4x - 5)²
= (9x + 1 - 4x + 5) (9x + 1 + 4x - 5)
= (5x + 6) (13x - 4)
k. (x + 3) (2x - 4) + 6x + x² + 9
= (x + 3) (2x - 4) + (x + 3)²
= (x + 3) (2x - 4 + x + 3)
= (x + 3) (3x - 1)
l. (3x - 5) (4x + 9) + 9x² - 25
= (3x - 5) (4x + 9) + (3x - 5) (3x + 5)
= (3x - 5) (4x + 9 + 3x + 5)
= (3x - 5) (7x + 14)
= 7 (x + 2) (3x - 5).
