a: \(\Leftrightarrow\left\{{}\begin{matrix}x>=1\\\left(2x-2\right)^2-\left(x-4\right)^2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=1\\\left(2x-2-x+4\right)\left(2x-2+x-4\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=1\\\left(x+2\right)\left(3x-6\right)=0\end{matrix}\right.\Leftrightarrow x=2\)
b: \(\Leftrightarrow\left|4x-\dfrac{1}{5}\right|\cdot\dfrac{7}{3}=\dfrac{9}{2}+\dfrac{1}{6}=\dfrac{14}{3}\)
\(\Leftrightarrow\left|4x-\dfrac{1}{5}\right|=2\)
\(\Leftrightarrow\left[{}\begin{matrix}4x-\dfrac{1}{5}=2\\4x-\dfrac{1}{5}=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}4x=\dfrac{11}{5}\\4x=-\dfrac{9}{5}\end{matrix}\right.\Leftrightarrow x\in\left\{\dfrac{11}{20};-\dfrac{9}{20}\right\}\)
