Ta có :
`f(x)=0`
`⇒ 3x^2-x=0`
`=> x(3x-1)=0`
$⇒ \left[ \begin{array}{l}3x-1=0\\x=0\end{array} \right.$
$⇒ \left[ \begin{array}{l}3x=1\\x=0\end{array} \right.$
$⇒ \left[ \begin{array}{l}x=\dfrac{1}{3}\\x=0\end{array} \right.$
Vậy `x={1/3;0}` thỏa mãn đề bài