a: \(\Leftrightarrow\left\{{}\begin{matrix}4x-12y-4z=-24\\4x-2y+4z=12\\4x-7y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-10y-8z=-36\\-5y-4z=-27\\4x-7y=3\end{matrix}\right.\)
=>Vô nghiệm
b: \(\Leftrightarrow\left\{{}\begin{matrix}-x-8z=-9\\8x+2z=24\\3x-y-7z=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{87}{31}\\z=\dfrac{24}{31}\\y=1\end{matrix}\right.\)
c: \(\Leftrightarrow\left\{{}\begin{matrix}8x-12y-16z=-8\\30x-12y-12z=18\\21x-12y-18z=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-22x-4z=-26\\-13x+2z=-11\\2x-3y-4z=-2\end{matrix}\right.\)
=>x=1 và z=1 và y=0
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