\(a,=27-27y+9y^2-y^3\\ b,=27x^3+54x^2y^2+36xy^4+8y^6\\ c,=x^3-6x^2y^2+27xy^4-27y^6\\ d,=\dfrac{1}{8}x^3-\dfrac{3}{4}x^2y+\dfrac{3}{2}xy^2-y^3\\ e,=\dfrac{1}{8}x^3+\dfrac{1}{4}x^2y+\dfrac{1}{6}xy^2+\dfrac{1}{27}y^3\\ f,=\dfrac{8}{27}x^3-\dfrac{8}{3}x^2y+8xy^2-8y^3\\ g,=\left(x+y+x-y\right)\left(x^2+2xy+y^2-x^2+y^2+x^2-2xy+y^2\right)\\ =2x\left(x^2+3y^2\right)\)