Đáp án:
$\begin{array}{l}
4{x^3} - x + 3 = 0\\
\Rightarrow 4{x^3} + 4{x^2} - 4{x^2} - 4x + 3x + 3 = 0\\
\Rightarrow \left( {x + 1} \right)\left( {4{x^2} - 4x + 3} \right) = 0\\
\Rightarrow \left[ \begin{array}{l}
x = - 1\\
4{x^2} - 4x + 3 = 0 \Rightarrow {\left( {2x - 1} \right)^2} + 2 = 0\left( {vn} \right)
\end{array} \right.\\
Vậy\,x = - 1
\end{array}$
