\[x^{2} + 4x = 0\]
\[x(x + 4) = 0\]
\[x = 0\ \ \ \ \ \ \ \ \ x + 4 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 4\]
\[Ответ:0;\ - 4.\]