Đáp án:
Giải thích các bước giải:
Bài 3:
\(\begin{array}{l}
3xy - 3x - 2y = 0 \to 3x\left( {y - 1} \right) - y - y = 0\\
\to 3x\left( {y - 1} \right) - \left( {y - 1} \right) - \left( {y - 1} \right) - 2 = 0\\
\to \left( {y - 1} \right)\left( {3x - 1 - 1} \right) = 2\\
\to \left( {y - 1} \right)\left( {3x - 2} \right) = 2\\
\to \left\{ {\left( {y - 1} \right);\left( {3x - 2} \right)} \right\} \in U\left( 2 \right)\\
\to \left\{ \begin{array}{l}
\left[ \begin{array}{l}
y - 1 = 2\\
y - 1 = - 2\\
y - 1 = 1\\
y - 1 = - 1
\end{array} \right. \to \left[ \begin{array}{l}
y = 3\\
y = - 1\\
y = 2\\
y = 0
\end{array} \right.\\
\left[ \begin{array}{l}
3x - 2 = - 2\\
3x - 2 = 2\\
3x - 2 = - 1\\
3x - 2 = 1
\end{array} \right. \to \left[ \begin{array}{l}
x = 0\\
x = \frac{4}{3}\left( l \right)\\
x = \frac{1}{3}\left( l \right)\\
x = 1
\end{array} \right.
\end{array} \right.
\end{array}\)
