\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
Solve by Gauss the \(3 \times 3\) system \(\{2 x + y + z = 4 \;;\; x + 3 y - z = 2 \;;\; x - y + 2 z = 1\}\).
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