a)
\(\sqrt{4x-8}+\sqrt{x-2}=5\\ < =>\sqrt{4\left(x-2\right)}+\sqrt{x-2}=5\\ < =>2\sqrt{x-2}+\sqrt{x-2}=5\\ < =>\sqrt{x-2}\left(2+1\right)=5\\ < =>\sqrt{x-2}=\frac{5}{3}\\ < =>x-2=\frac{25}{9}\\ ...\\ x=\frac{43}{9}\)
b)
\(\sqrt{9^2-6x+1}=3\\ < =>9^2-6x+1=9\\ < =>82-6x=9\\ 6x=73\\ < =>x=\frac{73}{6}\)