Tìm x biết x^2(3x-2) - 8 + 12x = 0

* Hướng dẫn giải

$\begin{array}{l}{\mathrm{x}}^2\left(3\mathrm{x}-2\right)-8+12\mathrm{x}=0\\ {\mathrm{x}}^2\left(3\mathrm{x}-2\right)+4\left(3\mathrm{x}-2\right)=0\\ \left(3\mathrm{x}-2\right)\left({\mathrm{x}}^2+4\right)=0\\ \Rightarrow 3\mathrm{x}-2=0\left(\mathrm{do}\mathrm{\hspace{0.17em}}{\mathrm{x}}^2+4>0\right)\\ \Rightarrow \mathrm{x}=\frac{2}{3}\end{array}$