Question

tìm GTNN : A= 4 I 2x - 1 I +3

Answer 1

\(A=4\left|2x-1\right|+3\ge0+3=3\)

\(\Rightarrow A_{min}=3\Leftrightarrow2x-1=0\Leftrightarrow x=\dfrac{1}{2}\)

Answer 2

\(4\left|2x-1\right|\ge0\left(\forall x\right)=>4\left|2x-1\right|+3\ge3\)

dấu= xảy ra <=>2x-1=0<=>x\(=\dfrac{1}{2}\)

\(=>A\ge3\)

vậy min A=3

Answer 3

Vì 4|2x - 1| \(\ge0\forall x\in R\Rightarrow A=4\left|2x-1\right|+3\ge3\forall x\in R\)

Dấu "=" xảy ra khi : \(4\left|2x-1\right|=0\Leftrightarrow x=\dfrac{1}{2}\)

Vậy MinA = 3 khi x = \(\dfrac{1}{2}\)