Question

find the expansion of (3x^2-2ax+3a^2)^3 using binomial theorem

Answer 1

3x2−a(2x−3a)]3=(3x2)3−3C1(3x2)2.a(2x−3a)+3C2(3x2)a2(2x−3a)2−a3(2x−3a)3

⇒27x6−27x4a(2x−3a)+9x2a2(4x2−12ax+9a2)−a3(8x3−3×4×x2×3a+3×2x×9a2−27a3)

⇒27x6−54x5a+81a2x4−108a3x3+81a4x2−8a3x3+36a4x2−54a5x+27a6

⇒27x6−54x5a+117a2x4−116a3x3+117a4x2−54a5x+27a6