a: Ta có: \(A=\dfrac{2\sqrt{x}}{\sqrt{x}-3}-\dfrac{x+9\sqrt{x}}{x-9}\)
\(=\dfrac{2x+6\sqrt{x}-x-9\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\)
\(=\dfrac{x-3\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\)
\(=\dfrac{\sqrt{x}}{\sqrt{x}+3}\)
Ta có: \(B=\dfrac{x+5\sqrt{x}}{x-25}\)
\(=\dfrac{\sqrt{x}\left(\sqrt{x}+5\right)}{\left(\sqrt{x}+5\right)\left(\sqrt{x}-5\right)}\)
\(=\dfrac{\sqrt{x}}{\sqrt{x}-5}\)
b:Ta có: P=A:B
\(=\dfrac{\sqrt{x}}{\sqrt{x}+3}:\dfrac{\sqrt{x}}{\sqrt{x}-5}\)
\(=\dfrac{\sqrt{x}-5}{\sqrt{x}+3}\)
Ta có: P-1
\(=\dfrac{\sqrt{x}-5-\sqrt{x}-3}{\sqrt{x}+3}\)
\(=\dfrac{-8}{\sqrt{x}+3}< 0\)
hay P<1
