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JEE Main 24 February 2021, Shift 2, Maths Q86

Question 86 of 90 in this shift, Maths question 26 of 30, Section B. NTA dropped this question from the final key; it is left out of every count on this site.

For integers n and r, let

\binom{n}{r}=\begin{cases}{}^{n}C_r, & \text{if } n\geq r\geq0\\ 0, & \text{otherwise}\end{cases}

The maximum value of

k

for which the sum

\sum_{i=0}^{k}\binom{10}{i}\binom{15}{k-i}+\sum_{i=0}^{k+1}\binom{12}{i}\binom{13}{k+1-i}

exists, is equal to ________.

Official answer

Dropped by NTA (marks given to all)

NTA final key: NTA final key 'D' = question dropped.

Chapter: Binomial Theorem
Topic: Binomial Coefficients
Idea tested: Vandermonde's Identity

JEE Main 24 February 2021, Shift 2, Maths Q86

Same idea in other shifts