We have (3x2−2ax+3a2)3
=[(3x2−2ax)+3a2]3
=3C0(3x2−2ax)3+3C1(3x2−2ax)2(3a2)+ 3C2(3x2−2ax)(3a2)2+3C3(3a2)3
=(3x2−2ax)3+3×3a2(3x2−2ax)2+ 3×9a4(3x2−2ax)+27a6
=(27x6−8a3x3−54ax5+36a2x4)+ 9a2(9x4+4a2x2−12ax3)+27a4(3x2−2ax)+27a6
=27x6−8a3x3−54ax5+36a2x4+81a2x4+36a4x2− 108a3x3+81a4x2−54a5x+27a6
=27x6−54ax5+117a2x4−116a3x3+117a4x2 −54a5x+27a6