\(B=\left|x-1\right|+\left|x-2\right|+\left|x-3\right|\)
\(B=\left|x-1\right|+\left|3-x\right|+\left|x-2\right|\)
\(B\ge\left|x-1+3-x\right|+\left|x-2\right|\)
\(B\ge2+\left|x-2\right|\)
\(B\ge2\)
Dấu "=" xảy ra khi:
\(\left\{{}\begin{matrix}x\ge1\\x=2\\x\le3\end{matrix}\right.\Leftrightarrow x=2\)