ГДЗ по алгебре 8 класс Мерзляк Задание 520

\[\boxed{\mathbf{520\ (520).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \frac{a(a - 5)}{(a - 5)^{2}} + \frac{25}{(a - 5)(a + 5)} =\]

\[= \frac{a}{a - 5} + \frac{25}{(a - 5)(a + 5)} =\]

\[= \frac{a² + 5a + 25}{(a - 5)(a + 5)}\]

\[2)\ \frac{a^{2} + 5a + 25}{(a - 5)(a + 5)}\text{\ \ }:\frac{125 - a^{3}}{5 + a} =\]

\[= - \frac{1}{(a - 5)^{2}}\]

\[при\ a = 4,5 \Longrightarrow - \frac{1}{(4,5 - 5)^{2}} =\]

\[= - \frac{1}{\left( - \frac{1}{2} \right)^{2}} = - 4.\ \]