JEE Main 2013MathematicsPermutation CombinationEasyMCQ

JEE Main 2013 — Permutation Combination Question with Solution

JEE Main 2013 (07 Apr)

Question

Let Tn be the number of all possible triangles formed by joining vertices of an n-sided regular polygon. If Tn+1-Tn=10, then the value of n is :

Choose an option

Show full solutionCorrect option: C
Correct answer
C5

Step-by-step explanation

Number of triangles =C3n

Given:C3n+1-C3n=10  

⇒n2-n-20=0  

⇒n-5n+4=0

⇒n=5,  ∵n≠0

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About this question

This is a previous-year question from JEE Main 2013, covering the Permutation Combination chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.