ĐKXĐ: \(x>1\)
\(A=\frac{\left(\sqrt{x-1}\right)^2}{\sqrt{x-1}}+\frac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}+1}=\sqrt{x-1}+\sqrt{x}+1\)
\(A=6\Rightarrow\sqrt{x-1}+\sqrt{x}+1=6\)
\(\Leftrightarrow\sqrt{x-1}+\sqrt{x}=5\)
\(\Leftrightarrow2x-1+2\sqrt{x^2-x}=25\)
\(\Leftrightarrow\sqrt{x^2-x}=13-x\) (\(x\le13\))
\(\Leftrightarrow x^2-x=x^2-26x+169\)
\(\Rightarrow x=\frac{169}{25}\)