Q43 / 90 · JEE Main 2024 (31 Jan Shift 1) · Mathematics

Let A=1, 2, 3, 4 and R=(1, 2), (2, 3), (1, 4) be a relation on A. Let S be the equivalence relation on A such that R⊂S and the number of elements in S is n. Then, the minimum value of n is _______

Correct answer: 16

Solution

Given,

A=1, 2, 3, 4 and R=(1, 2), (2, 3), (1, 4) be a relation on A.

Now, given S be the equivalence relation on A and R⊂S

So, for S to be equivalence it should be Reflexive, Symmetric and Transitive on given relation,

Now, for reflexive Relation we need, 1,1, 2,2, 3,3, 4,4→4 elements,

For Symmetric relation we need, 2,1, 3,2, 4,1→3 elements,

And for Transitive relation we need, 1,3, 3,1, 3,4, 4,2, 2,4, 4,3→6 elements

So, minimum 13 elements should be added in R

Hence , nS=16 elements.

Hence, the correct answer is 16.

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