\[1\ и\ - 5\sqrt{5} \Longrightarrow 1;x;y;\ \]
\[- 5\sqrt{5} \longrightarrow геометрическая\ \]
\[прогрессия \Longrightarrow\]
\[\Longrightarrow q = \frac{x}{1} = \frac{y}{x} = - \frac{5\sqrt{5}}{y}\]
\[\left\{ \begin{matrix} x = \frac{y}{x}\text{\ \ \ \ \ \ \ \ \ \ } \\ yx = - \frac{5\sqrt{5}}{y} \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = x^{2}\text{\ \ \ \ \ \ \ \ } \\ x^{3} = - 5\sqrt{5} \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = x^{2}\text{\ \ \ \ \ \ \ \ \ \ \ \ } \\ x^{3} = \left( - \sqrt{5} \right)^{3} \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ }\]
\[\left\{ \begin{matrix} y = x^{2}\text{\ \ \ } \\ x = - \sqrt{5} \\ \end{matrix} \right.\ \text{\ \ \ \ \ }\]
\[\left\{ \begin{matrix} x = - \sqrt{5} \\ y = 5\ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[Ответ:\ - \sqrt{5}\ \ и\ 5.\ \]