1: \(A=\dfrac{x-4}{\sqrt{x}\left(\sqrt{x}+2\right)}:\dfrac{\sqrt{x}+1}{\sqrt{x}}=\dfrac{\sqrt{x}-2}{\sqrt{x}}\cdot\dfrac{\sqrt{x}}{\sqrt{x}+1}=\dfrac{\sqrt{x}-2}{\sqrt{x}+1}\)
2: căn x-2<căn x+1
=>A<1
3: A=1/4
=>căn x-2/căn x+1=1/4
=>4 căn x-8=căn x+1
=>3 căn x=9
=>x=9