* TH1: Ta có: 17 = 17.1
Và: 2xy - 12x - 5y + 30 = (2x - 5) (y - 6)
Vì 2x - 5 luôn luôn lẻ với mọi x
\(\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}2x-5=17\\y-6=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=11\\y=7\end{matrix}\right.\\\left[{}\begin{matrix}2x-5=1\\y-6=17\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\y=23\end{matrix}\right.\end{matrix}\right.\left(TM\frac{ }{ }\right)\)
* TH2: Ta có: 17 = (-17) ( -1)
Tương tự, ta có:
2x - 5 luôn lẻ với mọi x
\(\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}2x-5=-17\\y-6=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-6\\y=5\end{matrix}\right.\\\left[{}\begin{matrix}2x-5=-1\\y-6=-17\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\y=-11\end{matrix}\right.\end{matrix}\right.\)(TM)
