ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 581

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Пояснение.

Решение.

\[\textbf{а)}\ x^{2} - 9x + 20 = 0\]

\[\left\{ \begin{matrix} x_{1} + x_{2} = 9 \\ x_{1}x_{2} = 20 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix} x_{1} = 4 \\ x_{2} = 5 \\ \end{matrix} \right.\ \]

\[\textbf{б)}\ y^{2} + 11y - 12 = 0\]

\[\left\{ \begin{matrix} y_{1} + y_{2} = - 11 \\ y_{1}y_{2} = - 12\ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix} y_{1} = - 12 \\ y_{2} = 1\ \ \ \ \ \\ \end{matrix} \right.\ \]

\[\textbf{в)}\ y^{2} + y - 56 = 0\]

\[\left\{ \begin{matrix} y_{1} + y_{2} = - 1 \\ y_{1}y_{2} = - 56\ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix} y_{1} = 7\ \ \\ y_{2} = - 8 \\ \end{matrix} \right.\ \]

\[\textbf{г)}\ z^{2} - 19z + 88 = 0\]

\[\left\{ \begin{matrix} z_{1} + z_{2} = 19 \\ z_{1}z_{2} = 88\ \ \ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\left\{ \begin{matrix} z_{1} = 11 \\ z_{2} = 8\ \ \\ \end{matrix} \right.\ \]