a) $\sqrt{9-6x-}$$x^{2}$ =3
⇔ $\sqrt{(x-3)}$$^{2}$ =3
⇔$\left[\begin{matrix} x-3=3\\ x-3=-3\end{matrix}\right.$
⇔$\left[\begin{matrix} x=6\\ x=0\end{matrix}\right.$
b) $\sqrt{1-10x+25}$$x^{2}-$ $\text{x+5}$=$\text{0}$
⇔$\sqrt{(5x-1)}$$^{2}$ = $\text{x-5}$
⇔l$\text{5x-1}$l$\text{=x-5}$ ⇔$\left[\begin{matrix} 5x-1=x-5\\ 5x-1=5+x\end{matrix}\right.$$\Leftrightarrow$$\left[\begin{matrix} 4x=-4\\ 4x=6\end{matrix}\right.$
⇔$\left[\begin{matrix} x=-1\\ x=3/2\end{matrix}\right.$
c) $\sqrt{x-2}$ = $\sqrt{2x-5}$
⇔ $\sqrt{(x-2)}$$^{2}$ = $\sqrt{(2x-5)}$$^{2}$
⇔$\text{x-2 = 2x-5}$
⇔$\text{5-2 = 2x-x}$
⇔$\text{x=3}$
