Giải thích các bước giải:
\(\begin{array}{l}
\left\{ \begin{array}{l}
y = 2x + 2\\
mx + 2x + 2 = 5
\end{array} \right. \to \left\{ \begin{array}{l}
x = \frac{3}{{m + 2}}\\
y = \frac{{6 + 2m + 4}}{{m + 2}}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = \frac{3}{{m + 2}}\\
y = \frac{{10 + 2m}}{{m + 2}} = \frac{{2m + 4 + 6}}{{m + 2}} = 2 + \frac{6}{{m + 2}}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = \frac{3}{{m + 2}}\\
y = 2 + \frac{6}{{m + 2}}
\end{array} \right.\\
b.Do:x,y \in Z\\
\to \left\{ \begin{array}{l}
\frac{3}{{m + 2}} \in Z\\
\frac{6}{{m + 2}} \in Z
\end{array} \right.\\
\to m + 2 \in UC\left( {3;6} \right)\\
\to \left[ \begin{array}{l}
m + 2 = 3\\
m + 2 = - 3\\
m + 2 = 1\\
m + 2 = - 1
\end{array} \right. \to \left[ \begin{array}{l}
m = 1\\
m = - 5\\
m = - 1\\
m = - 3
\end{array} \right.\\
c.Do:\\
\left\{ \begin{array}{l}
x = \frac{3}{{m + 2}}\\
y = 2 + \frac{6}{{m + 2}}
\end{array} \right. \to - 2x + y = \frac{{ - 6}}{{m + 2}} + 2 + \frac{6}{{m + 2}} = 2\\
\to - 2x + y = 2
\end{array}\)
