- $$\frac{a-1}{a+2} \cdot \frac{1}{a^2-4a} = \frac{a-1}{(a+2)a(a-4)}$$
- $$\frac{a-1}{(a+2)a(a-4)} + \frac{1}{a+2} = \frac{a-1 + a(a-4)}{(a+2)a(a-4)} = \frac{a-1 + a^2 - 4a}{(a+2)a(a-4)} = \frac{a^2 - 3a - 1}{a(a+2)(a-4)}$$
Ответ: $$\frac{a^2 - 3a - 1}{a(a+2)(a-4)}$$