\(B=\dfrac{\sqrt{5}\left(\sqrt{x}-1\right)}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}+\dfrac{9-\sqrt{x}}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{5\sqrt{x}-5+9-\sqrt{x}}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}=\dfrac{4\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{4}{\sqrt{x}-1}\)
3.
\(P=AB=\dfrac{\sqrt{x}-1}{\sqrt{x}+2}.\dfrac{4}{\sqrt{x}-1}=\dfrac{4}{\sqrt{x}+2}\)
\(P>1\Rightarrow\dfrac{4}{\sqrt{x}+2}>1\Rightarrow4>\sqrt{x}+2\) (do \(\sqrt{x}+2>0\))
\(\Rightarrow\sqrt{x}< 2\Rightarrow x< 4\)
\(\Rightarrow x=\left\{0;2;3\right\}\)
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