Với mọi x ta có :
\(\left|1-x\right|\ge0\)
\(\Leftrightarrow\left|1-x\right|+8\ge0\)
\(\Leftrightarrow A\ge8\)
Dấu "=" xảy ra \(\Leftrightarrow\left|1-x\right|=0\)
\(\Leftrightarrow x=1\)
Vậy \(A_{Min}=8\Leftrightarrow x=1\)
A=|1-x|+8
\(\left|1-x\right|\ge0\forall x\)
=> \(\left|1-x\right|+8\ge8\)
=>A ≥ 8
GTNN A =8
khi 1-x=0
=> x=1
vậy GTNN A =8 khi x=1