Answer: (n+1)th term with coefficient 2nCn.
- A (n+1)th term with coefficient 2nCn
- B nth term, taken as the halfway point before adjusting for indexing
- C (2n)th term, the very last term in the expansion
- D C(n,n), the coefficient of the final term x2n
Correct answer: A. (n+1)th term with coefficient 2nCn
Explanation: Expansion of (1+x)2n has 2n+1 terms. Middle term is (n+1)th term: C(2n,n) × xn.
Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.
Concept context
Counting, arrangements, and selections