\[\boxed{\text{467\ (467).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[(x - 3) \cdot (x + 1 - x) = ax\]
\[(x - 3) \cdot 1 = ax\]
\[x - 3 = ax\]
\[x - ax = 3\]
\[x \cdot (1 - a) = 3\]
\[при\ a = 1:\ \ \]
\[x \cdot 0 = 3 - корней\ нет.\]
\[Ответ:при\ a = 1.\]
\[(5x - 1) \cdot a - 4x + 2a = 0\]
\[5ax - a - 4x + 2a = 0\]
\[5ax - 4x + a = 0\]
\[5ax - 4x = - a\]
\[x \cdot (5a - 4) = - a\]
\[5a - 4 = 0\]
\[a = \frac{4}{5} = 0,8.\]
\[x \cdot 0 = - 0,8 - корней\ нет\]
\[Ответ:при\ a = 0,8.\]
\[- 10x + 2ax = 7 + 5a\]
\[- 2x \cdot (5 - a) = 7 + 5a\]
\[5 - a = 0\]
\[a = 5.\]
\[- 2x \cdot 0 = 7 + 25 - корней\ нет.\]
\[Ответ:при\ a = 5.\ \ \]