1: Thay x=16 vào A, ta được:
\(A=\dfrac{4-1}{4+3}=\dfrac{3}{7}\)
2: \(P=A:B\)
\(=\dfrac{\sqrt{x}-1}{\sqrt{x}+3}:\dfrac{x-3\sqrt{x}-x-6\sqrt{x}-9+x+11\sqrt{x}+6}{x-9}\)
\(=\dfrac{\sqrt{x}-1}{1}\cdot\dfrac{\sqrt{x}-3}{x+2\sqrt{x}-3}=\dfrac{\sqrt{x}-3}{\sqrt{x}+3}\)