tìm x: x^3 (3x -2) -8 + 12x = 0

* Hướng dẫn giải

$\begin{array}{l}{\mathrm{x}}^3\left(3\mathrm{x}-2\right)-8+12\mathrm{x}=0\\ \Rightarrow {\mathrm{x}}^3\left(3\mathrm{x}-2\right)+4\left(3\mathrm{x}-2\right)=0\\ \iff \left(3\mathrm{x}-2\right)\left({\mathrm{x}}^3+4\right)=0\Rightarrow \left[\begin{array}{l}\mathrm{x}=\frac{2}{3}\\ \mathrm{x}=\sqrt[3]{-4}\end{array}\right.\end{array}$