Question

Tim  GTNN cua 

\(A=x^2-\frac{1}{3}x+\frac{1}{27x}+2016...\)

Answer 1

Ta có

\(A=x^2-\frac{x}{3}+\frac{1}{27x}+2016\)

\(=\left(x^2-\frac{2x}{3}+\frac{1}{9}\right)+\left(\frac{x}{3}-\frac{2}{9}+\frac{1}{27x}\right)+2016-\frac{1}{9}+\frac{2}{9}\)

\(=\left(x-\frac{1}{3}\right)^2+\left(\frac{\sqrt{x}}{\sqrt{3}}-\frac{1}{3\sqrt{3x}}\right)^2+\frac{18145}{9}\)

\(\ge\frac{18145}{9}\)

Dấu  = xảy ra khi \(x=\frac{1}{3}\)

PS: Lần sau đừng chép đề thiếu nữa nha bạn :(

Answer 2

x>0 nhe

Answer 3

\(min_A=\frac{1469648}{729}\Leftrightarrow x=\frac{4}{27}\)

Answer 4

Alibab  si 1 ty nhe .