\[\boxed{\mathbf{958\ (958).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[x^{2} - (2a - 1)x + a^{2} - a -\]
\[- 6 = 0;\ \ x_{1,2} \in \lbrack - 3;2\rbrack\]
\[D = (2a - 1)^{2} -\]
\[- 4 \cdot \left( a^{2} - a - 6 \right) = 4a^{2} - 4a +\]
\[+ 1 - 4a^{2} + 4a + 24 = 25\]
\[x_{1} = \frac{2a - 1 + 5}{2} = \frac{2a + 4}{2} =\]
\[= a + 2\]
\[x_{2} = \frac{2a - 1 - 5}{2} = \frac{2a - 6}{2} =\]
\[= a - 3\]
\[\left\{ \begin{matrix} - 3 \leq a + 2 \leq 2 \\ - 3 \leq a - 3 \leq 2 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]
\[\ \left\{ \begin{matrix} - 5 \leq a \leq 0 \\ 0 \leq a \leq 5 \\ \end{matrix} \right.\ \Longrightarrow \ \ a = 0\]
\[Ответ:0.\]