\[\left\{ \begin{matrix} y = x^{2} + 4x \\ y - x = 4\ \ \ \ \ \\ \end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix} y = x^{2} + 4x \\ y = x + 4\ \ \ \ \ \\ \end{matrix} \right.\ \]
\[x = - 4;\ \ x = 1.\]
\[Ответ:( - 4;0);(1;5).\]