Question Detail
Question
Determine the value of n if the coefficients of the sixth and eleventh terms in the binomial expansion of (x + y)^n are the same.
Correct Answer
Option B is the correct answer.
Detailed Explanation
In binomial expansion, coefficient of rth term is C(n, r-1). For sixth term: r=6, coefficient = C(n,5). For eleventh term: r=11, coefficient = C(n,10). Since C(n,5) = C(n,10), and C(n,k) = C(n,n-k), we have 5 = n-10 or 5 = 10? Actually, C(n,5) = C(n,10) implies either 5 = 10 (false) or 5 + 10 = n → n = 15.
Hint
Use the property that C(n,k) = C(n,n-k).