a: \(\Leftrightarrow\left\{{}\begin{matrix}x>=12\\\left(5x-1-x+12\right)\left(5x-1+x-12\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=12\\\left(4x+11\right)\left(6x-13\right)=0\end{matrix}\right.\Leftrightarrow x\in\)
b: \(\Leftrightarrow\left|2x\right|=3x+4\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=-\dfrac{4}{3}\\\left(2x-3x-4\right)\left(2x+3x+4\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=-\dfrac{4}{3}\\\left(-x-4\right)\left(5x+4\right)=0\end{matrix}\right.\)
=>x=-4/5
c: \(\Leftrightarrow\left|2x-1\right|=3x-x+3=2x+3\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=-\dfrac{3}{2}\\\left(2x-1-2x-3\right)\left(2x-1+2x+3\right)=0\end{matrix}\right.\Leftrightarrow x=-\dfrac{1}{2}\)
