Question Detail
Question
If nCr + nCr+1 = n+1Cx, then x = ?
Correct Answer
Option D is the correct answer.
Detailed Explanation
This is a direct application of Pascal's Identity for combinations, which states: nCr + nC(r+1) = (n+1)C(r+1).Comparing the given equation nCr + nCr+1 = n+1Cx with Pascal's Identity, we can see that x must be equal to r+1.
Hint
Recognize this as Pascal's Identity: nCr + nC(r-1) = n+1Cr, or in this form, nCr + nC(r+1) = n+1C(r+1).