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JEE Advanced2025MathematicsSets and RelationsActual

Let the set of all relations R on the set a, b, c, d, e, f , such that R is reflexive and symmetric, and R contains exactly 10 elements, be denoted by S . Then the number of elements in S is ______

Correct answer

0

Step-by-step solution

For relation to be reflexive all the diagonal elements must be taken and out of remaining 30 elements there are 15 pairs and we need 2 pairs such that R contains exactly 10 elements and is both reflexive and symmetric. number of ways = ¹⁵ C ₂=105

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