\[|x| \leq 5\\\to \left[ \begin{array}{l}|x|=5\\|x|=4\\|x|=3\\|x|=2\\|x|=1\\|x|=0\end{array} \right.\\\to \left[ \begin{array}{l}x=5\\x=5\\x=4\\x=-4\\x=3\\x=-3\\x=2\\x=-2\\x=1\\x=-1\\x=0\end{array} \right.\\\to \text{Tổng các số nguyên là}\\5-5+4-4+3-3+2-2+1-1+0=0\]
