\[5x² - 30x = 0\]
\[5x(x - 6) = 0\]
\[x = 0\ \ \ \ \ \ \ \ \ x - 6 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 6\]
\[Ответ:x = 0;x = 6.\]