\[\boxed{\mathbf{751\ (751).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[a_{1} = y^{2} + 1,\ \ a_{2} = y^{2} + y,\ \ \]
\[a_{3} = 8y - 10.\ \ \]
\[Тогда:\ \ \ \ 2a_{2} = a_{1} + a_{3}\]
\[2 \cdot \left( y^{2} + y \right) = y^{2} + 1 + 8y - 10\]
\[2y^{2} + 2y = y^{2} + 8y - 9\]
\[y^{2} - 6y + 9 = 0\]
\[(y - 3)^{2} = 0\]
\[y = 3\]
\[a_{1} = 9 + 1 = 10,\]
\[\text{\ \ }a_{2} = 9 + 3 = 12,\ \ \]
\[a_{3} = 24 - 10 = 14.\ \]
\[Ответ:y = 3;\ a_{1} = 10,\ \]
\[a_{2} = 12,\ a_{3} = 14\text{.\ }\]