A) p^3+3p^2q+3pq^2+q^3 - p(p^2-2pq+q^2)=p^3+3p^2q+3pq^2+q^3 - p^3+2p^2q-pq^2= 5p^2q+2pq^2+q^3
б) m^3+n^3-(m^3+3m^2n+3mn^2+n^3)=m^3+n^3-m^3-3m^2n-3mn^2-n^3=-3m^2n-3mn^2
в) 8x^3+12x^2y+6xy^2+y^3-6x^2y-6xy^2= 8x^3 + 6x^2y+ y^3
г) 3b (a^2+6ab+9b^2)-(a^3+9a^2b+ 27ab^2+27b^3)= 3a^2b+18ab^2+ 27b^3-a^3-9a^2b-27ab^2-27b^3= -6a^2b-9ab^2-a^3