JEE Main 2026 · 2 Apr · Shift 2 · Mathematics Q7

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MathematicsSingle correct+4 / -1Question 7 of 75

Let $P_n$ denote the total number of triangles formed by joining the vertices of an $n$ -side regular polygon. If $P_{n+1}-P_n=66$ , then the sum of all distinct prime divisors of $n$ is :

Answer and worked solution

Official answer: C

Count. $P_n={}^nC_3$ , so $P_{n+1}-P_n={}^nC_2=66$ and $n=12$ .

Primes. $12=2^2\cdot3$ , sum $2+3=5$ .

(C)

Topics:Combinations

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JEE Main 2026 · 2 Apr · Shift 2, Mathematics question 7