Question

tìm x để P đạt GTNN

P= cănx -1 phần cănx+2

Answer 1

\(P=\dfrac{\sqrt{x}+2-3}{\sqrt{x}+2}=1-\dfrac{3}{\sqrt{x}+2}\)

\(\sqrt{x}+2>=2\)

=>\(\dfrac{3}{\sqrt{x}+2}< =\dfrac{3}{2}\)

=>\(-\dfrac{3}{\sqrt{x}+2}>=-\dfrac{3}{2}\)

=>\(P=\dfrac{-3}{\sqrt{x}+2}+1>=-\dfrac{3}{2}+1=-\dfrac{1}{2}\)

Dấu = xảy ra khi x=0