8) =a²b+a2+b2+a2b2 =

8) Выражение содержит опечатку, исправляю ее.

$$\frac{1}{5}a^2b^2 + \frac{2}{5}a^2b + \frac{3}{5}ab^2 + \frac{4}{5}a^2b^2 = (\frac{1}{5} + \frac{4}{5})a^2b^2 + \frac{2}{5}a^2b + \frac{3}{5}ab^2 = \frac{5}{5}a^2b^2 + \frac{2}{5}a^2b + \frac{3}{5}ab^2 = a^2b^2 + \frac{2}{5}a^2b + \frac{3}{5}ab^2$$

Ответ: $$a^2b^2 + \frac{2}{5}a^2b + \frac{3}{5}ab^2$$