ĐKXĐ: x>=3
\(25\sqrt{\dfrac{x-3}{25}}-7\sqrt{\dfrac{4x-12}{9}}-7\sqrt{x^2-9}+18\sqrt{\dfrac{9x^2-81}{81}}=0\)
=>\(25\cdot\dfrac{\sqrt{x-3}}{5}-7\cdot\sqrt{x-3}\cdot\dfrac{2}{3}-7\sqrt{x^2-9}+18\cdot\sqrt{\dfrac{x^2-9}{9}}=0\)
=>\(\dfrac{61}{3}\cdot\sqrt{x-3}-7\sqrt{x^2-9}+2\sqrt{x^2-9}=0\)
=>\(\dfrac{61}{3}\sqrt{x-3}-5\cdot\sqrt{x^2-9}=0\)
=>\(\sqrt{x-3}\left(\dfrac{61}{3}-5\sqrt{x+3}\right)=0\)
=>\(\left[{}\begin{matrix}x-3=0\\5\sqrt{x+3}=\dfrac{61}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x-3=0\\\sqrt{x+3}=\dfrac{61}{15}\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=3\\x+3=\dfrac{3721}{225}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\left(nhận\right)\\x=\dfrac{3721}{225}-3=\dfrac{3046}{225}\left(nhận\right)\end{matrix}\right.\)
