a(a+2b)3-b(2a+b)3=a(a3-6a2b-12ab2-8b3
=b(8a3+12a2b+6ab2+b2)
=a4+6a2b+12a2b2+8ab2-8a3b-12a2b2-6ab3-b4
= a4-2a3b-2ab3-b4
=(a4-b4)-(2a3b-2ab2)
=(a2-b2)(a2+b2)-2ab(a2-b2)
=(a-b)(a+b)(a2+b2-2ab)
=(a-b)(a+b)(a-b)2-(a-b)3(a+b)
Chúc bạn làm tốt nhé !!!