8) a³ - a²b - a² + ab; 9) x + 4y + x² - 16y²; 10) x²y - x²y - x³ + x³.

8) $a^3 - a^2b - a^2 + ab = a^2(a - b) - a(a - b) = a(a-1)(a-b)$ 9) $x + 4y + x^2 - 16y^2 = (x + 4y) + (x - 4y)(x + 4y) = (x + 4y)(1 + x - 4y)$ 10) $x^2y - x^2y - x^3 + x^3 = 0$