a: ĐKXĐ: x>0; x<>1; x<>4
\(P=\dfrac{\sqrt{x}-\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}-1\right)}:\dfrac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)-\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}\)
\(=\dfrac{1}{\sqrt{x}\cdot\left(\sqrt{x}-1\right)}\cdot\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}{3}=\dfrac{\sqrt{x}-2}{3\sqrt{x}}\)
\(P-1=\dfrac{\sqrt{x}-2-3\sqrt{x}}{3\sqrt{x}}=\dfrac{-2\sqrt{x}-2}{3\sqrt{x}}< 0\)
=>P<1
b: Khi x=1/4 thì \(P=\dfrac{\dfrac{1}{2}-2}{3\cdot\dfrac{1}{2}}=-\dfrac{3}{2}:\dfrac{3}{2}=-1\)
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