JEE Main 2025 — Sets And Relations Question with Solution
From: JEE Main 2025 (Online) 3rd April Evening Shift
Question
Let . Let R be a relation on defined by if and only if . Let be the number of elements in R . Let and be the minimum number of elements required to be added in R to make it reflexive and symmetric relations, respectively. Then is equal to
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Show full solutionCorrect option: B
Step-by-step explanation
To solve the problem, we start by defining the set and the relation on set , where an element is related to (written as ) if and only if .
This leads us to the following pairs in the relation :
For , , so is in .
For , , so is in .
For , , so is in .
For , , so is in .
For , , so is in .
For , , so is in .
Thus, the relation consists of the pairs: , and there are elements in .
Making the Relation Reflexive
A relation is reflexive if every element in the set relates to itself. Therefore, the missing reflexive pairs are:
Adding these three pairs will make the relation reflexive, so .
Making the Relation Symmetric
A relation is symmetric if whenever is in , must also be in . Therefore, the missing symmetric pairs are:
Thus, we need to add these three pairs for symmetry, so .
Finally, we calculate the sum .
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This is a previous-year question from JEE Main 2025, covering the Sets And Relations 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.