(2x - 3)² - 5x(2x - 3) =
= (2x - 3)(2x - 3) - 5x(2x - 3)
= (2x - 3)(2x - 3 - 5x)
= (2x - 3)(- 3x - 3)
= -3(2x - 3)(x + 1)