Tìm xy nguyên thoả mã a,y(x-3)+3x-9=11 b,xy+5y-2y-7=0

$\begin{array}{l}a,y\left( {x - 3} \right) + 3x - 9 = 11\\ \Leftrightarrow y\left( {x - 3} \right) + 3\left( {x - 3} \right) = 11\\ \Leftrightarrow \left( {x - 3} \right)\left( {y + 3} \right) = 11\\ + )\,\left\{ \begin{array}{l}x - 3 = 11\\y + 3 = 1\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x = 14\\y =  - 2\end{array} \right.\\ + )\,\left\{ \begin{array}{l}x - 3 = 1\\y + 3 = 11\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x = 4\\y = 8\end{array} \right.\\ + )\,\left\{ \begin{array}{l}x - 3 =  - 1\\y + 3 =  - 11\end{array} \right. \Rightarrow \left\{ \begin{array}{l}x = 2\\x =  - 14\end{array} \right.\\ + )\left\{ \begin{array}{l}x - 3 =  - 11\\y + 3 =  - 1\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x =  - 8\\y =  - 4\end{array} \right.\end{array}$

Câu b) xem lại đề bài bạn nhé