Помогите с алгеброй! !!! 293 (1, 2)

293
1)
$\frac{a+b}{15ab}* \frac{30a^2b}{a^2-b^2} - 1 = \frac{a+b}{15ab}* \frac{30a^2b}{(a-b)*(a+b)}-1= \frac{2a}{a-b}-1 \\ \\ a=2 \\ b=-2 \\ \\ \frac{2 * 2}{2-(-2)}-1= \frac{4}{4}-1=0$

2)
$\frac{4ab-4b^2}{a^4+a}: \frac{5a-5b}{a^3+1}+20= \frac{4b*(a-b)}{a*(a^3+1)} * \frac{a^3+1}{5*(a-b)}+20= \frac{4b}{5a}+20 \\ \\ a=5 \\ b=-4 \\ \\ \frac{4*(-4)}{5*5}+20 = - \frac{16}{25}+20=19 \frac{9}{25}$