ĐKXĐ: x>=3
\(5\sqrt{\dfrac{9x-27}{25}}-7\cdot\sqrt{\dfrac{4x-12}{9}}=3\)
=>\(5\cdot\sqrt{\dfrac{9}{25}}\cdot\sqrt{x-3}-7\cdot\sqrt{\dfrac{4}{9}}\cdot\sqrt{x-3}=3\)
=>\(5\cdot\dfrac{3}{5}\sqrt{x-3}-7\cdot\dfrac{2}{3}\sqrt{x-3}=3\)
=>\(-\dfrac{5}{3}\cdot\sqrt{x-3}=3\)(vô lý)
Vậy: \(x\in\varnothing\)