1. (1+b)(1-b) =1-b².
2.225-16m^8 =15² -(4m^4)² =(15 -4m^4)(15 +4m^4) .
3. (14b -15c)² =(14b)² -2*14b*15c +(15c)² =196b² -420bc +225c².
4) (13 -12 n^5)² =13² -2*13*12 n^5+(12^n^5) =169 - 312 n^5 +144 n^10 .
5) 25 с² - 20 cm + 4m² =(5c)² -2*5c*2m+(2m)² =(5c-2m)².