a: \(\Leftrightarrow\left\{{}\begin{matrix}5x+10y-3y=-1\\2x+4-3x+15y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5x+7y=-1\\-x+15y=-16\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}5x+7y=-1\\-5x+75y=-80\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=-\dfrac{81}{82}\\x=\dfrac{97}{82}\end{matrix}\right.\)
c: \(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{2}x+\dfrac{1}{4}-\dfrac{1}{3}y+\dfrac{2}{3}=\dfrac{1}{12}\\\dfrac{1}{2}x+\dfrac{5}{2}-\dfrac{1}{3}y-\dfrac{7}{3}=-4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{2}x-\dfrac{1}{3}y=-\dfrac{5}{6}\\\dfrac{1}{2}x-\dfrac{1}{3}y=-\dfrac{25}{6}\end{matrix}\right.\)(vô lý)
Vậy: Hệ pt vô nghiệm
