a)\(P=\left(\sqrt{x}-\dfrac{x+3}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{\sqrt{x}-9}{1-x}\right)\)
\(P=\left(\dfrac{\sqrt{x}\left(\sqrt{x}+1\right)-x-3}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)-9+\sqrt{x}}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)
\(P=\left(\dfrac{\sqrt{x}-3}{\sqrt{x}+1}\right):\left(\dfrac{x-9}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)
\(P=\dfrac{\sqrt{x}-1}{\sqrt{x}+3}\)
b)\(x\ge0\Rightarrow\sqrt{x}\ge0\ge\sqrt{x}+3\ge3\)
\(\)\(\Rightarrow\sqrt{x}-1\ge0\Leftrightarrow x\ge1\)
Vậy \(P_{min}\) =0 tại x=1
Đúng 1
Bình luận (0)
