1) (3x - 5)² - 9 = (3x - 5)² - 3² = (3x - 5 - 3)(3x - 5 + 3) = (3x - 8)(3x - 2)
2) (5x + 3)² - 25 = (5x - 3)² - 5² = (5x - 3 - 5)(5x - 3 + 5) = (5x - 8)(5x + 2)
3) 16 - (x - 3)² = 4² - (x - 3)² = [4 - (x - 3)][4 + (x - 3)] = (4 - x + 3)(4 + x - 3) =
= (7 - x)(x + 1)
4) 121 - (5 - 7x)² = 11² - (5 - 7x)² = [11 - (5 - 7x)][11+ (5 - 7x)] = (11 - 5 + 7x)(11+ 5 - 7x)=
= (7x + 6)(16 - 7x)