Question

Tìm GTNN của A = \(\dfrac{x^2}{x^4+x^2+1}\)

Answer 1

\(A=\dfrac{x^2}{x^4+x^2+1}=\dfrac{x^2}{x^4+x^2+\dfrac{1}{4}+\dfrac{3}{4}}=\dfrac{x^2}{\left(x^2+\dfrac{1}{2}\right)^2+\dfrac{3}{4}}\ge0\)

"=" Khi x=0

Answer 2

Ta có: \(x^2\ge0\)

\(x^4+x^2+1\ge0\)

\(\Rightarrow A=\dfrac{x^2}{x^4+x^2+1}\ge0\)

A_MIN = 0 khi x = 0