Đáp án:
\[\left[ \begin{array}{l}
\left\{ \begin{array}{l}
x = 3\\
y = 0
\end{array} \right.\\
\left\{ \begin{array}{l}
x = 1\\
y = - 2
\end{array} \right.
\end{array} \right.\]
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
xy + x - 2y = 3\\
\Leftrightarrow x\left( {y + 1} \right) - 2y - 2 = 3 - 2\\
\Leftrightarrow x\left( {y + 1} \right) - 2\left( {y + 1} \right) = 1\\
\Leftrightarrow \left( {x - 2} \right)\left( {y + 1} \right) = 1\\
\Leftrightarrow \left[ \begin{array}{l}
\left\{ \begin{array}{l}
x - 2 = 1\\
y + 1 = 1
\end{array} \right.\\
\left\{ \begin{array}{l}
x - 2 = - 1\\
y + 1 = - 1
\end{array} \right.
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
\left\{ \begin{array}{l}
x = 3\\
y = 0
\end{array} \right.\\
\left\{ \begin{array}{l}
x = 1\\
y = - 2
\end{array} \right.
\end{array} \right.
\end{array}\)
