Упрощение выражений

1. $$\frac{2a}{a-2} + \frac{a+7}{8-4a} \cdot \frac{32}{7a+a^2} = \frac{2a}{a-2} + \frac{a+7}{-4(a-2)} \cdot \frac{32}{a(7+a)} = \frac{2a}{a-2} - \frac{8}{a(a-2)} = \frac{2a^2 - 8}{a(a-2)} = \frac{2(a^2 - 4)}{a(a-2)} = \frac{2(a-2)(a+2)}{a(a-2)} = \frac{2(a+2)}{a} = \frac{2a+4}{a}$$
2. $$\left(\frac{a-1}{a+1} - \frac{a+1}{a-1}\right) : \frac{2a}{1-a^2} = \frac{(a-1)^2 - (a+1)^2}{(a+1)(a-1)} : \frac{2a}{1-a^2} = \frac{a^2-2a+1 - (a^2+2a+1)}{a^2-1} : \frac{2a}{1-a^2} = \frac{-4a}{a^2-1} : \frac{2a}{1-a^2} = \frac{-4a}{a^2-1} \cdot \frac{1-a^2}{2a} = \frac{-4a}{-(1-a^2)} \cdot \frac{1-a^2}{2a} = \frac{-4a}{1} \cdot \frac{1}{2a} = -2$$