\(\Rightarrow\left[{}\begin{matrix}x-4,7=3\\4,7-x=3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=7,7\\x=1,7\end{matrix}\right.\)
\(\left[{}\begin{matrix}x-4,7=3\\x-4,7=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7,7\\x=1,7\end{matrix}\right.\)