(3a - 2b)² - (3a + 2b)² = (3a - 2b - 3a - 2b)(3a - 2b + 3a + 2b) = -4b * 6a = - 24ab
9(2x - y)² - (5x - y)² = [3(2x - y)]² - (5x - y)² = (6x - 3y - 5x + y)(6x - 3y + 5x - y) =
= (x - 2y)(11x - 4y)
4(a - 3b)² - 9(5a - 4b)² = [2(a - 3b)]² - [3(5a - 4b)]² =
= (2a - 6b - 15a + 12b)(2a - 6b + 15a - 12b) = (6b - 13a)(17a - 18b)