\[\boxed{\mathbf{146}.}\]
\[y = x^{2} + px + q;\ \ \ \]
\[x\ и\ y - корни\ уравнения.\]
\[x + y = 8;\ \ x \cdot y = q;\]
\[x^{2} - 8x + q = 0\]
\[1)\ D = 64 - 4q\]
\[64 - 4q \geq 0\]
\[4q \leq 64\]
\[q \leq 16.\]
\[q_{\max} = 16.\]
\[2)\ D = 0:\]
\[x = y = \frac{8}{2} = 4.\]
\[Ответ:x + y = 4 + 4.\]