а) (2х+у)^3-х^3=((2x+y)-x)*((2x+y)^2+(2x+y)x+x^2)=(2x+y-x)*(4x^2+4xy+y^2+2x^3+xy+x^2)=(x+y)*(7x^2+5xy+y^2)
б)8p^3-(p+1)^3=(2p-(p-1))*(4p^×+2p*(p+1)+(p+1)^2)=(2p-p-1)*(4p^2+2p^2+2p+p^3+1)=(p-1)*(7p^2+4p+1)
в) (5х+4)^2-(4х-5)^2=(5x+4-(4x-5))*(5x+4+4x-5)=(5x+4-4x+5)*(9x-1)=(x+9)*(9x-1)