Đáp án:
$\begin{array}{l}
3{x^6} - 4{x^5} + 2{x^4} - 8{x^3} + 2{x^2} - 4x + 3\\
= 3{x^6} + 3{x^5} + 6{x^4} + 3{x^3} + 3{x^2} - 7{x^5} - 7{x^4} - 14{x^3} - 7{x^2} - 7x + 3{x^4} + 3{x^3} + 6{x^2} + 3x + 1\\
= 3{x^2}\left( {{x^4} + {x^3} + 2{x^2} + x + 1} \right) - 7x\left( {{x^4} + {x^3} + 2{x^2} + x + 1} \right) + 3\left( {{x^4} + {x^3} + 2{x^2} + x + 1} \right)\\
= \left( {3{x^2} - 7x + 3} \right)\left( {{x^4} + {x^3} + 2{x^2} + x + 1} \right)\\
= \left( {3{x^2} - 7x + 3} \right){\rm{[}}{x^2}\left( {{x^2} + x + 1} \right) + \left( {{x^2} + x + 1} \right){\rm{]}}\\
{\rm{ = }}\left( {3{x^2} - 7x + 3} \right)\left( {{x^2} + 1} \right)\left( {{x^2} + x + 1} \right)
\end{array}$
