ĐKXĐ: \(x\le3\)
\(\sqrt{25\left(3-x\right)}+\sqrt{3-x}-\sqrt{16\left(3-x\right)}=1\)
\(\Leftrightarrow5\sqrt{3-x}+\sqrt{3-x}-4\sqrt{3-x}=1\)
\(\Leftrightarrow2\sqrt{3-x}=1\)
\(\Leftrightarrow\sqrt{3-x}=\dfrac{1}{2}\)
\(\Leftrightarrow3-x=\dfrac{1}{4}\)
\(\Rightarrow x=\dfrac{11}{4}\)