1. а) (с-5)(с+2) = с²+2с-5с-10 = с²-3с-10
б) (6d+1)(d-3) = 6d²-18d+d-3 = 6d²-17d-3
в) (4m-n)(m+5n) = 4m²+20mn-mn-5n² = 4m²+19mn-5n²
г) (у+3)(у²-3у-4) = у³-3у²-4у+3у²-9у-12 = у³-13у-12
2. а) а(2n-1)+3(2n-1) = (2n-1)(a+3)
б) 2c-2d+bc-bd = 2(c-d)+b(c-d) = (c-d)(2+b)