\[\boxed{\mathbf{728\ (728).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[x^{2} + 4x + n = 0\]
\[3 \cdot \left( - 4 - x_{2} \right) - x_{2} = 8\]
\[- 12 - 3x_{2} - x_{2} = 8\]
\[- 4x_{2} = 20\]
\[x_{2} = - 5\]
\[x_{1} = - 4 - x_{2} = - 4 + 5 = 1\]
\[x_{1}x_{2} = n\]
\[- 5 \cdot 1 = - 5\]
\[Ответ:\ x_{1} = 1;\ \ x_{2} = - 5;\ \ \]
\[n = - 5.\]