\(\left\{{}\begin{matrix}x+y+z=224\\-5x+3y+5z=0\\x-2z=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}3x+3y+3z=672\left(1\right)\\-5x+3y+5z=0\left(2\right)\\x-2z=0\left(3\right)\end{matrix}\right.\)
\(\left(1\right)-\left(2\right)\Leftrightarrow8x-2z=672\)
\(\Leftrightarrow4x-z=336\left(4\right)\)
\(\left(3\right);\left(4\right)\Leftrightarrow\left\{{}\begin{matrix}x-2z=0\\4x-z=336\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}4x-8z=0\\4x-z=336\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}7z=336\\x-2z=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=96\\z=48\end{matrix}\right.\)
\(\Rightarrow y=224-96-48=80\)
Vậy nghiệm hpt đã cho là \(\left\{{}\begin{matrix}x=96\\y=80\\z=48\end{matrix}\right.\)