\[\boxed{\mathbf{716\ (716).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[x_{1} = 7\]
\[x_{2} = ?\]
\[x² + px - 42 = 0\]
\[x_{1} \cdot x_{2} = - 42\]
\[x_{2} = - \frac{42}{x_{1}} = - \frac{42}{7} = - 6\]
\[x_{1} + x_{2} = - p\]
\[7 - 6 = 1 \Longrightarrow \ \ p = - 1\]
\[Ответ:x_{2} = - 6;\ \ p = - 1.\]