g: Ta có: \(\sqrt{x-5}+\sqrt{4x-20}-\dfrac{1}{5}\sqrt{9x-45}=3\)
\(\Leftrightarrow\sqrt{x-5}+2\sqrt{x-5}-\dfrac{1}{5}\cdot3\sqrt{x-5}=3\)
\(\Leftrightarrow\sqrt{x-5}\cdot\dfrac{12}{5}=3\)
\(\Leftrightarrow\sqrt{x-5}=\dfrac{5}{4}\)
\(\Leftrightarrow x-5=\dfrac{25}{16}\)
hay \(x=\dfrac{105}{16}\)