(a-b)(a+b)(a^4+a^2 b^2+b^4)=(a^2-b^2)(a^4+a^2 b^2+b^4)=
=a^6+a^4b^2+a^2b^4-a^4b^2-a^2b^4-b^6=a^6-b^6
(a-b)(a+b)(a^4+a^2 b^2+b^4)=(a^2-b^2)(a^4+a^2 b^2+b^4)=
=a^6+a^4b^2+a^2b^4-a^4b^2-a^2b^4-b^6=a^6-b^6