- Ta có: \(\left|3x-3\right|\ge0\forall x\)
\(\Rightarrow\left|3x-3\right|-111\ge-111\)
\(\Rightarrow A_{min}=-111\)
- Dấu "=" xảy ra khi \(\left|3x-3\right|=0\)
\(\Leftrightarrow3x-3=0\)
\(\Leftrightarrow3x=3\)
\(\Leftrightarrow x=1\)
Vậy \(A_{min}=-111\)\(\Leftrightarrow\)\(x=1\)