8. Сократите дробь: a) $$\frac{x^2 - y^2}{y^3 - x^3}$$; b) $$\frac{2a^4b^3 + 8a^3b^4 + 8a^2b^5}{5a^2b^2 + 10ab^3}$$.

a) $$\frac{x^2 - y^2}{y^3 - x^3} = \frac{(x - y)(x + y)}{(y - x)(y^2 + xy + x^2)} = \frac{-(y - x)(x + y)}{(y - x)(x^2 + xy + y^2)} = \frac{-(x + y)}{x^2 + xy + y^2} = -\frac{x + y}{x^2 + xy + y^2}$$. b) $$\frac{2a^4b^3 + 8a^3b^4 + 8a^2b^5}{5a^2b^2 + 10ab^3} = \frac{2a^2b^3(a^2 + 4ab + 4b^2)}{5ab^2(a + 2b)} = \frac{2a^2b^3(a + 2b)^2}{5ab^2(a + 2b)} = \frac{2ab(a + 2b)}{5} = \frac{2ab(a + 2b)}{5}$$. Ответ: a) $$-\frac{x + y}{x^2 + xy + y^2}$$; b) $$\frac{2ab(a + 2b)}{5}$$.