a: \(\Leftrightarrow\left\{{}\begin{matrix}8x+2y=4\\8x+3y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=1\\x=\dfrac{1}{4}\end{matrix}\right.\)
b: \(\Leftrightarrow\left\{{}\begin{matrix}3x=m+4\\x-y=m\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{3}m+\dfrac{4}{3}\\y=\dfrac{1}{3}m+\dfrac{4}{3}-m=-\dfrac{2}{3}m+\dfrac{4}{3}\end{matrix}\right.\)
c: \(\Leftrightarrow\left\{{}\begin{matrix}3x+2y=6\\2x-2y=4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x=10\\x-y=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=0\end{matrix}\right.\)
d: Vì \(\dfrac{2}{-4}=\dfrac{-3}{6}< >\dfrac{1}{2}\)
nên hệ phương trình vô nghiệm
