\[16x^{3} + 8x^{2} + x = 0\]
\[x \cdot (4x + 1)^{2} = 0\]
\[x = 0\ \ \ \ \ \ \ \ \ \ \ \ \ \ 4x + 1 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4x = - 1\ \ \]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - \frac{1}{4} = - 0,25\]
\[Ответ:x = 0;\ x = - 0,25.\]