Question

TÌM  GTLN hoặc GTNN

\(C=x^2-2x+2018\)

Answer 1

\(C=x^2-2x+2018=\left(x^2-2x+1\right)+2017=\left(x-1\right)^2+2017\ge2017.\)

Dấu "='' xảy ra khi x=1 

Answer 2

\(C=x^2-2x+2018=x^2-2x+1+2017=\left(x-1\right)^2+2017\)

Vì: \(\left(x-1\right)^2\ge0\forall x\)

\(\Rightarrow\left(x-1\right)^2+2017\ge2017\forall x\)

Vậy Min C = 2017

Dấu = xảy ra khi: \(\left(x-1\right)^2=0\Rightarrow x=1\)

=.= hok tốt!!