a: \(Q=\sqrt{x}\left(\dfrac{x-1-x-\sqrt{x}-1+x+2}{x\sqrt{x}-1}\right)\)
\(=\sqrt{x}\cdot\dfrac{x-\sqrt{x}}{x\sqrt{x}-1}\)
\(=\dfrac{x}{x+\sqrt{x}+1}\)
b: \(P=\dfrac{1}{Q}-3\sqrt{x}=\dfrac{x+\sqrt{x}+1}{x}-3\sqrt{x}\)
\(=\dfrac{x+\sqrt{x}+1-3x\sqrt{x}}{x}>0\)
=>1/Q>3 căn x