Đặt \(S=\left|x+2019\right|+\left|x+2020\right|+\left|x+2021\right|\)
\(=\left(\left|x+2019\right|+\left|x+2021\right|\right)+\left|x+2020\right|\)
\(=\left(\left|x+2019\right|+\left|-x-2021\right|\right)+\left|x+2020\right|\ge\left|x+2019+\left(-x-2021\right)\right|+0=0\)
Dấu " = " xảy ra \(\Leftrightarrow x=-2020\)
Vậy \(Min_S=2\)