Đk: \(x\ge3\)
PT \(\Leftrightarrow25.\dfrac{\sqrt{x-3}}{5}-7.\sqrt{\dfrac{4\left(x-3\right)}{9}}-7\sqrt{x^2-9}+18\sqrt{\dfrac{9\left(x^2-9\right)}{81}}=0\)
\(\Leftrightarrow5\sqrt{x-3}-\dfrac{14}{3}\sqrt{x-3}-7\sqrt{x^2-9}+6\sqrt{x^2-9}=0\)
\(\Leftrightarrow\dfrac{1}{3}\sqrt{x-3}-\sqrt{x^2-9}=0\)
\(\Leftrightarrow\sqrt{x-3}\left(\dfrac{1}{3}-\sqrt{x+3}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x-3}=0\\\dfrac{1}{3}=\sqrt{x+3}\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=3\left(TM\right)\\x=\dfrac{-26}{9}\left(L\right)\end{matrix}\right.\)
Vậy..