1) 625-(n+12)²=(25-n-12)(25+n+12)=(13-n)(37+n)
2) 121-(b-13)²=(11-b+13)(11+b-13)=(24-b)(b-2)
3) (m+10)²-(n-12)²=(m+10-n+12)(m+10+n-12)=(m-n+22)(m+n-2)
4) (c-1)²-(d-23)²=(c-1-d+23)(c-1+d-23)=(c-d+22)(c+d-24)
5) (15z+4)²-(3z-2)²=(15z+4-3z+2)(15z+4+3z-2)=(12z+6)(17z+2)
6) (13t-9)²-(8t-7)²=(13t-9-8t+7)(13t-9+8t-7)=(5t-2)(21t-16)