\(x\left(2x-1\right)+\dfrac{1}{3}-\dfrac{2}{3}x=0\)
\(\Leftrightarrow x\left(2x-1\right)+\dfrac{1}{3}\left(1-2x\right)=0\)
\(\Leftrightarrow x\left(2x-1\right)-\dfrac{1}{3}\left(2x-1\right)=0\)
\(\Leftrightarrow\left(x-\dfrac{1}{3}\right)\left(2x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-\dfrac{1}{3}=0\\2x-1=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{1}{2}\end{matrix}\right.\)