Question 23
Binomial TheoremDetermine the coefficient of x2 in the expansion of (a + 3x)6.
- A.18a2
- B.45a4
- C.135a4
- D.1215a2
Show the answer and explanation
Answer: C (135a4)
Explanation
The x2 term is 6C2a4(3x)2 = 15 × 9a4x2, so the coefficient is 135a4.