Hoặc
.aa+2b3−b2a+b3=aa3+6a2b+12ab2+8b3−b8a3+12a2b+6ab2+b3
=a4+6a3b+12a2b2+8ab3−8a3b−12a2b2−6ab3−b4
=a4−2a3b+2ab3−b4
=a4−b4−2a3b−2ab3
=a2−b2a2+b2−2aba2−b2=a2−b2a2−2ab+b2
=a−ba+ba−b2=a−b3a+b