\(\Leftrightarrow\left\{{}\begin{matrix}5x+2y-7z=6\\2x+3y+2z=7\\9x+8y-3z=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}90x+36y-126z=108\\90x+135y+9z=315\\90x+80y-30z=10\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}-99y-135z=-207\\-44y-96z=98\\2x+3y+2z=7\end{matrix}\right.\)
=>y=613/66; z=-95/18; x=-2041/396
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