Đặt A= \(x^2+2x+2019=\left(x^2+2x+1\right)+2018\)
\(=\left(x+1\right)^2+2018\)
Vì \(\left(x+1\right)^2\ge0\forall x\)
nên : \(\left(x+1\right)^2+2018\ge2018\forall x\)
Dấu "=" xảy ra \(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
Vậy : min A = 2018 tại x = -1