Respuesta :

[tex] x^{2} -10x=39~~~~~~~~~~~|+25 \\ x^{2} -10x+25=64 \\ (x-5)^2=64 \Rightarrow x-5=8,~or~x-5=-8. \\ x-5=8 \Rightarrow x=13. \\ x-5=-8 \Rightarrow x=-3. \\ \\ \underline{Solution}: \boxed{x \in \{-3;13\}}.[/tex]