Вопрос:

Ответ:

\[r^{2} - s^{2} - 10s - 25 =\]

\[= r^{2} - \left( s^{2} + 10s + 25 \right) =\]

\[= r^{2} - (s + 5)^{2} =\]

\[= (r - s - 5)(r + s + 5).\]