\[x^{2} + x + q = 0\]
\[x_{1} - x_{2} = 4\]
\[x_{1} = 4 + x_{2}\]
\[x_{1} + x_{2} = - 1\]
\[4 + x_{2} + x_{2} = - 1\]
\[2x_{2} = - 5\]
\[x_{2} = - 2,5.\]
\[x_{1} + 2,5 = 4\]
\[x_{1} = 1,5.\]
\[q = x_{1} \cdot x_{2} = - 3,75.\]
\[Ответ:q = - 3,75.\]