Verified answer

(x-2y)^3 + (x+2y)^3 = x^3 - 6x^2y + 6xy^2 - 8y^3 + x^3 + 6x^2y + 6xy^2 + 8y^3 =

= 2x^3 + 12xy^2 = 2x(x^2+6y^2)

сумма кубов ((х-2у)+(х+2у))*((х-2у)^2-(х-2у)*(х+2у)+(х+2у)^2)=2х*((х^2-4xy+4y^2)-(x^2-4y^2)+(x^2+4xy+4y^2))=2x*(x^2-4xy+4y^2-x^2+4y^2+x^2+4xy+4y^2)=2x*(12y^2+x^2)

вроде так