\(\left(3-4x\right)^2-3\left(4x-3\right)=0\)
=>\(\left(4x-3\right)^2-3\left(4x-3\right)=0\)
=>\(\left(4x-3\right)\left(4x-3-3\right)=0\)
=>\(\left(4x-3\right)\left(4x-6\right)=0\)
=>\(\left[{}\begin{matrix}4x-3=0\\4x-6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{4}\\x=\dfrac{6}{4}=\dfrac{3}{2}\end{matrix}\right.\)