ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 776

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\[x^{2} + px + q = 0,\ \ x_{1}^{2} + x_{2}^{2} - ?\]

\[\left\{ \begin{matrix} x_{1} + x_{2} = - p \\ x_{1}x_{2} = q\ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]

\[x_{1}^{2} + x_{2}^{2} = x_{1}^{2} + 2x_{1}x_{2} + x_{2}^{2} -\]

\[- 2x_{1}x_{2} = \left( x_{1} + x_{2} \right)^{2} - 2x_{1}x_{2} =\]

\[= ( - p)^{2} - 2q =\]

\[= p^{2} - 2q\]

\[Ответ:p^{2} - 2q.\ \]