Question

Tìm GTNN của F = \(4x^2-4x+3\)

Answer 1

Có: \(F=4x^2-4x+3\)

\(\Rightarrow F=4\left(x^2-x+\dfrac{3}{4}\right)\)

\(\Rightarrow F=4\left(x^2-2.\dfrac{1}{2}x+\dfrac{1}{4}+\dfrac{1}{2}\right)\)

\(\Rightarrow F=4\left(x-\dfrac{1}{2}\right)^2+2\ge2\)

Dấu ''='' xảy ra khi \(\left(x-\dfrac{1}{2}\right)^2=0\Rightarrow x=\dfrac{1}{2}\)