a^8+a^4b^4+b^8=a^8+2a^4b^4+b^8-a^4b^4=(a^4+b^4)^2-(a^2b^2)^2=(a^4+b^4+a^2b^2)(a^4+b^4-a^2b^2)=(a^2+b^2+ab)(a^2+b^2-ab)(a^4+b^4-a^2b^2)