Нужно преобразовать произведение в многочлен.

^2 - значит "в квадрате"
1) = ac+ad+bc+bd
2) = ab-ac+2b-2c
3) = a^2 + ab-2a-a-b+2 = a^2 + ab -3a -b +2
4) = a^2+ab-ab-b^2 = a^2-b^2
5) = a^2 + ab +ab + b^2 = a^2+2ab+b^2
6) = xz + xt + yz + yt
7) = xy -xz +2y -2x
8) = x^2 +xy -3x -x -y +3 = x^2 +xy -4x -y +3
9) = x^2 +xy -xy -y^2 = x^2 -y^2
10) = x^2 +x +x+1 = x^2 +2x+1
11) = mp+mq+np+nq
12) - mn-mp+2n-2p
13) = m^2 +mn-2m-m-n+2 = m^2 -mn-m-n+2
14) = m^2 +mp -mp -p^2 = m^2 -p^2
15) = m^2 +2m +2m +4 = m^2 +4m+4