a, \(\left\{{}\begin{matrix}8x+2y=-10\\3x-2y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}11x=-22\\y=-5-4x\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=3\end{matrix}\right.\)
c, \(\left\{{}\begin{matrix}x+5y=-9\\x-5y=11\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x=2\\y=\dfrac{x-11}{5}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-2\end{matrix}\right.\)
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