\(A=\frac{\sqrt{x}\left(\sqrt{x}+5\right)-10\sqrt{x}-5\left(\sqrt{x}-5\right)}{\left(\sqrt{x}-5\right)\left(\sqrt{x}+5\right)}\) ĐKXĐ: x\(\ge\) 0; x\(\ne\) 25
\(=\frac{x+5\sqrt{x}-10\sqrt{x}-5\sqrt{x}+25}{\left(\sqrt{x}+5\right)\left(\sqrt{x}-5\right)}=\frac{x-5\sqrt{x}+25}{\left(\sqrt{x}+5\right)\left(\sqrt{x}-5\right)}\)
Để A>0\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-5\sqrt{x}+25>0\\x-25>0\end{matrix}\right.\\\left\{{}\begin{matrix}x-5\sqrt{x}+25< 0\\x-25< 0\end{matrix}\right.\end{matrix}\right.\)
Có \(x-5\sqrt{x}+25>0\forall x\Rightarrow\left\{{}\begin{matrix}x-5\sqrt{x}+25>0\\x>25\end{matrix}\right.\)
\(\Rightarrow x>25\)
