Question

A=-\(\sqrt{x}-x+2\)(tìm giá trị lớn nhất)

Answer 1

\(A=-\left(x+\sqrt[]{x}+\dfrac{1}{4}\right)+\dfrac{9}{4}=-\left(\sqrt{x}+\dfrac{1}{2}\right)^2+\dfrac{9}{4}\le-\left(0+\dfrac{1}{2}\right)^2+\dfrac{9}{4}=2\)

\(maxA=2\Leftrightarrow x=0\)

Answer 2

\(=-\left(\sqrt{x}+\dfrac{1}{2}\right)^2+\dfrac{9}{4}\le2\forall x\)

Dấu '=' xảy ra khi x=0