Rút gọn được \(A=\dfrac{\sqrt{x}}{\sqrt{x}-3}\)

\(B-8A\le0\Leftrightarrow\dfrac{x+16}{\sqrt{x}-3}-\dfrac{8\sqrt{x}}{\sqrt{x}-3}\le0\)

\(\Leftrightarrow\dfrac{x-8\sqrt{x}+16}{\sqrt{x}-3}\le0\)

\(\Leftrightarrow\dfrac{\left(\sqrt{x}-4\right)^2}{\sqrt{x}-3}\le0\)

\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}-4=0\\\sqrt{x}-3< 0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=16\\x< 9\end{matrix}\right.\)

Kết hợp ĐKXD ta được: \(\left[{}\begin{matrix}x=16\\0\le x< 9\end{matrix}\right.\)

a) \(\left\{{}\begin{matrix}x\ge0\\x\ne\dfrac{5}{3}\end{matrix}\right.\)

b) \(x\ne\dfrac{1}{2}\)

c) \(\left[{}\begin{matrix}x>\dfrac{1}{2}\\x< -5\end{matrix}\right.\)

thay cái ảnh nền giùm cái !!!!