a: \(M=\dfrac{x+\sqrt{x}+1-x+\sqrt{x}-1+x+1}{\sqrt{x}}=\dfrac{x+2\sqrt{x}+1}{\sqrt{x}}=\dfrac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}}\)
b: Để M=9/2 thì \(\dfrac{x+2\sqrt{x}+1}{\sqrt{x}}=\dfrac{9}{2}\)
=>2x-5 căn x+2=0
=>(căn x-2)(2 căn x-1)=0
=>x=1/4 hoặc x=4
c: \(M-4=\dfrac{\left(\sqrt{x}-1\right)^2}{\sqrt{x}}>0\)
=>M>4