\[\ x² < 3,4x\]
\[x^{2} - 3,4x < 0\]
\[x² - 3,4x = 0\]
\[x(x - 3,4) = 0\ \]
\[x = 0\ \ \ \ \ \ \ x - 3,4 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = 3,4\]
\[Ответ:x \in (0;3,4).\]