\(\Leftrightarrow\left\{{}\begin{matrix}8x+2y=-10\\3x-2y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}11x=-22\\4x+y=-5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=-5-4x=-5-4\cdot\left(-2\right)=-5+8=3\end{matrix}\right.\)
\(HPT\Leftrightarrow\left\{{}\begin{matrix}-8x-2y=10\\3x-2y=-12\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}-11x=22\\3x-2y=-12\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-2\\3.\left(-2\right)-2y=-12\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=3\end{matrix}\right.\)
Vậy hệ phương trình có nghiệm duy nhất là \(\left(-2;3\right)\)
\(\left\{{}\begin{matrix}4x+y=-5\\3x-2y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}8x+2y=-10\\3x-2y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}11x=-22\\4x+y=-5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=3\end{matrix}\right.\)
