a) \(4x-9=0\)
\(\Leftrightarrow4x=9\)
\(\Leftrightarrow x=\dfrac{9}{4}\)
b) \(3x\left(2x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\2x=1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\end{matrix}\right.\)
c) \(5x^2-x^3=0\)
\(\Leftrightarrow x^2\left(5-x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\end{matrix}\right.\)