a: \(B=\dfrac{x+3\sqrt{x}+2-2x+4\sqrt{x}-5\sqrt{x}-2}{x-4}\cdot\dfrac{\left(\sqrt{x}+2\right)^2}{\sqrt{x}\left(3-\sqrt{x}\right)}\)
\(=\dfrac{-x+2\sqrt{x}}{\sqrt{x}-2}\cdot\dfrac{1}{\sqrt{x}\left(3-\sqrt{x}\right)}=\dfrac{1}{\sqrt{x}-3}\)
b: B=2
=>căn x-3=1/2
=>căn x=7/2
=>x=49/4
c: B<0
=>căn x-3<0
=>0<x<9