Answer: nC1 an-1 b.
- A nCn-1 a bn-1
- B n an-1 b²
- C nC2 an-2 b²
- D nC1 an-1 b
Correct answer: D. nC1 an-1 b
Explanation: T2 = T(1+1) = nC1 an-1 b1 = n an-1 b.
Row n of Pascal's triangle gives the coefficients nC0, nC1, ..., nCn for the expansion of (a+b)ⁿ; each number is the sum of the two numbers diagonally above it, a direct visual proof of the identity nCr = (n-1)C(r-1) + (n-1)Cr.
Concept context
Expansion of (a+b) n , general term, middle term, binomial coefficients, and greatest term