\[5x^{2} + 2x = 0\]
\[x(5x + 2) = 0\]
\[x = 0\ \ \ \ \ \ \ \ \ 5x + 2 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - \frac{2}{5}\]
\[Ответ:x = 0;\ x = - 0,4.\]