[tex]\displaystyle\bf\\x^{2} -25=0\\\\x^{2} -5^{2} =0\\\\(x-5)\cdot(x+5)=0\\\\\\\left[\begin{array}{ccc}x-5=0\\x+5=0\end{array}\right\\\\\\\left[\begin{array}{ccc}x_{1}=5 \\x_{2} =-5\end{array}\right\\\\\\Otvet \ : \ 5 \ ; \ -5[/tex]