ta có:
\(2xy+y-3x=7\\ \Leftrightarrow4xy+2y-6x=14\\ \Leftrightarrow2y\left(2x+1\right)-3\left(2x+1\right)=11\\ \Leftrightarrow\left(2x+1\right)\left(2y-3\right)=11=1.11=11.1=\left(-1\right)\left(-11\right)=\left(-11\right)\left(-1\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}2x+1=+01\\2y-3=+11\end{matrix}\right.\\\left\{{}\begin{matrix}2x+1=+11\\2y-3=+01\end{matrix}\right.\\\left\{{}\begin{matrix}2x+1=-01\\2y-3=-11\end{matrix}\right.\\\left\{{}\begin{matrix}2x+1=-11\\2y-3=-01\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x=0\\y=4\end{matrix}\right.\\\left\{{}\begin{matrix}x=5\\y=2\end{matrix}\right.\\\left\{{}\begin{matrix}x=-1\\y=-4\end{matrix}\right.\\\left\{{}\begin{matrix}x=-6\\y=01\end{matrix}\right.\end{matrix}\right.\)
bạn tự kết luận x nha, trên đây mình có giải sai cái x,y đầu tiên, nghĩa là \(\left\{{}\begin{matrix}x=0\\y=4\end{matrix}\right.\)phải là\(\left\{{}\begin{matrix}x=0\\y=7\end{matrix}\right.\)
