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