1. b^2 - 121c^2 = (b - 11c)(b + 11c)
2.169m^2 - 16n^2 = (13m - 4n)(13m + 4n)
3. a^2b^4 - 9c^2 = (ab^2 - 3c)^2
4. p^3 - t ^3 = (p - t)(p^2 + pt + t^2)
5. 27 - p^3 = (3 - p)(9 + 3p + p^2)
6. c^2 - 2cm + m^2 = (c - m)^2
7. 9 + 6c + c^2 = (3 + c)^2
8. 81c^2 - 36cm + 4m^2 = (9c - 2m)^2
9. 25c^2 + 10cm^2 + m^4 = (5с + m^2)^2