\(\left|x+1\right|+\left|y+2\right|+\left|x-y+z\right|=0\)
\(\Rightarrow\left\{{}\begin{matrix}x+1=0\\y+2=0\\x-y+z=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-1\\y=-2\\-1-\left(-2\right)+z=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-1\\y=-2\\z=-1\end{matrix}\right.\)
Vậy (x;y;z) = (-1;-2;-1) thì GTBT bằng 0.