Với mọi x ta có :
\(\left|x-7\right|\ge0\)
\(\Leftrightarrow\left|x-7\right|+2018\ge2018\)
\(\Leftrightarrow A\ge2018\)
Dấu "=" xảy ra khi :
\(\left|x-7\right|=0\)
\(\Leftrightarrow x=7\)
Vậy \(A_{Min}=2018\Leftrightarrow x=7\)
Tìm cực trị à?
\(A=\left|x-7\right|+2018\)
Vì \(\left|x-7\right|\ge0\)
\(\Rightarrow\left|x-7\right|+2018\ge2018\)
\(\Rightarrow Min_A=2018\) khi \(\left|x-7\right|=0\Rightarrow x-7=0\Rightarrow x=7\)
Vậy \(Min_A=0\) khi x=7