\(\left(3x-2\right)\left(4x+5\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}3x-2=0\\4x+5=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}3x=2\\4x=-5\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-\dfrac{5}{4}\end{matrix}\right.\)
Vậy \(x\in\left\{\dfrac{2}{3};-\dfrac{5}{4}\right\}\)