Решебник по алгебре 8 класс Макарычев ФГОС Задание 322

 

\[\boxed{\text{322\ (322).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

Пояснение.

Решение.

\[\textbf{а)}\ 80 + y^{2} = 81\]

\[y^{2} = 81 - 80\]

\[y^{2} = 1\]

\[y = \pm \sqrt{1}\]

\[y = \pm 1.\]

\[\textbf{б)}\ 19 + c^{2} = 10\]

\[c^{2} = 10 - 19\]

\[c^{2} = - 9 < 0\]

\(c = \varnothing\).

\[\textbf{в)}\ 20 - b^{2} = - 5\]

\[b^{2} = 20 + 5\]

\[b = 25\]

\[b = \pm \sqrt{25}\]

\[b = \pm 5.\]

\[\textbf{г)}\ 3x^{2} = 1,47\]

\[x^{2} = 1,47\ :3\]

\[x^{2} = 0,49\]

\[x = \pm \sqrt{0,49}\]

\[x = \pm 0,7.\]

\[\textbf{д)}\ \frac{1}{4}a^{2} = 10\]

\[a^{2} = 10\ :\frac{1}{4} = 10 \cdot 4\]

\[a^{2} = 40\]

\[a = \pm \sqrt{40}\]

\[a = \pm 2\sqrt{10}.\]

\[\textbf{е)} - 5y^{2} = 1,8\]

\[y^{2} = 1,8\ :( - 5) < 0\]

\[y = \varnothing.\]

\[\boxed{\text{322.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]

Пояснение.

Решение.

\[\textbf{а)}\ \left( \sqrt{7} \right)^{2} = 7\]

\[\textbf{б)}\ \left( - \sqrt{26} \right)^{2} = 26\]

\[\textbf{в)} - 2\sqrt{14} \cdot \sqrt{14} = - 2 \cdot 14 =\]

\[= - 28\]

\[\textbf{г)}\ \left( 3\sqrt{5} \right)^{2} = 9 \cdot 5 = 45\]

\[\textbf{д)}\ 0,5 \cdot \left( - \sqrt{8} \right)^{2} = 0,5 \cdot 8 = 4\]

\[\textbf{е)}\ \left( - 2\sqrt{15} \right)^{2} = 4 \cdot 15 = 60\]

\[\textbf{ж)}\ \left( \frac{\sqrt{3}}{2} \right)^{2} = \frac{3}{4} = 0,75\]

\[\textbf{з)}\ \left( \frac{\sqrt{3}}{\sqrt{6}} \right)^{2} = \left( \sqrt{\frac{3}{6}} \right)^{2} = \frac{3}{6} = \frac{1}{2} =\]

\[= 0,5\]