Решебник по алгебре 7 класс Мерзляк Задание 583

\[\boxed{\text{583\ (583).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1){\ (a + 3)}^{2} - (a - 9)(a + 9) =\]

\[= a^{2} + 6a + 9 - a^{2} + 81 =\]

\[= 6a + 90\]

\[a = - 2,5:\]

\[- 6 \cdot 2,5 + 90 = 90 - 15 = 75.\]

\[x = - \frac{1}{3}:\]

\[9 \cdot \left( - \frac{1}{3} \right)^{2} - 30 \cdot ( - \frac{1}{3} + 55 =\]

\[= 9 \cdot \frac{1}{9} + \frac{30}{3} + 55 =\]

\[= 1 + 10 + 55 = 66.\]

\[y = \frac{1}{2}:\]

\[36 \cdot \left( \frac{1}{2} \right)^{4} + 30 = 36 \cdot \frac{1}{16} + 30 =\]

\[= 30\frac{9}{4} = 32\frac{1}{4}.\]