6) a² - 4a + 4 : (a - 2); a+2

6) $$\frac{a^2-4a+4}{a+2} : (a-2) = \frac{(a-2)^2}{a+2} \cdot \frac{1}{a-2} = \frac{(a-2)(a-2)}{(a+2)(a-2)} = \frac{a-2}{a+2}$$

Ответ: $$\frac{a-2}{a+2}$$