\[\boxed{\text{1167\ (1167).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[(3x - 1)(x + a) =\]
\[= (3x - 2)(x + 1)\]
\[3x^{2} + 3\text{ax} - x - a =\]
\[= 3x^{2} + 3x - 2x - 2\]
\[3\text{ax} - 2x = a - 2\]
\[x \cdot (3a - 2) = a - 2\]
\[3a - 2 = 0\]
\[3a = 2\]
\[a = \frac{2}{3}\]
\[Ответ:a = \frac{2}{3}\text{.\ }\]