Answer: -35x.
- A -35x
- B 35/x
- C 35x
- D -35/x
Correct answer: A. -35x
Explanation: T4 = 7C3 x7-3 x (-1/x)3 = 7C3 x4 x (-1/x3) = -7C3 x = -35x.
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