Question

Tim GTNN cua A=\(\frac{7}{x^2-x+2}\)

Answer 1

Phải là tìm GTLN chứ ?

Ta có :

\(A=\frac{7}{x^2-x+2}=\frac{7}{\left(x^2-x+\frac{1}{4}\right)+1,75}\)

\(=\frac{7}{\left(x-\frac{1}{2}\right)^2+1,75}\le\frac{7}{1,75}=4\)

\(\Leftrightarrow Max_A=4\Rightarrow x=\frac{1}{2}\)

Vậy ...