Question

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Answer 1

Ответ:

a) $\frac{5(a-5)}{a^{2}-25}$=$\frac{5(a-5)}{(a-5)(a+5)}$=$\frac{5}{a+5}$=$\frac{5}{-4,5+5}$=$\frac{5}{0,5}$=10

г) $\frac{4c^{2}-81}{4c^{2}+36c+81}$=$\frac{(2c-9)(2c+9)}{(2c+9)^{2}}$=$\frac{2c-9}{2c+9}$=$\frac{2*2,5-9}{2*2,5+9}$=$\frac{-4}{14}$=$-\frac{4}{14}$=$-\frac{2}{7}$