\[\boxed{\mathbf{636\ (636).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ x^{2} - nx + 3 = 0;\ \ \ x = 6\]
\[36 - 6n + 3 = 0\]
\[6n = 39\]
\[n = \frac{39}{6} = 6,5\]
\[Ответ:при\ n = 6,5.\]
\[2)\ nx^{2} - 8x + 10 = 0;\ \ \ x = 0,5\]
\[0,25n - 4 + 10 = 0\]
\[0,25n = - 6\]
\[n = - 24\]
\[Ответ:при\ n = - 24.\]