1:
1: Khi x=36 thì \(A=\dfrac{36-4}{3+3}=\dfrac{32}{6}=\dfrac{16}{3}\)
2: \(B=\dfrac{2x+6\sqrt{x}-x-9\sqrt{x}}{x-9}=\dfrac{x-3\sqrt{x}}{x-9}=\dfrac{\sqrt{x}}{\sqrt{x}+3}\)
3: \(P=A:B=\dfrac{\sqrt{x}}{\sqrt{x}+3}:\dfrac{x-4}{\sqrt{x}+3}=\dfrac{\sqrt{x}}{x-4}\)
P<0
=>x-4<0
=>0<=x<4
=>\(x\in\left\{0;1;2;3\right\}\)