Câu 4:
a: \(\Leftrightarrow\left\{{}\begin{matrix}2x+2y-3x+3y=5\\3x+3y+2x-2y=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-x+5y=5\\25x+5y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-26x=0\\-x+5y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\y=1\end{matrix}\right.\)