JEE Main20231 Feb 2023Evening ShiftMathematicsSets and RelationsActual
Let P S denote the power set of S = 1 , 2 , 3 , … , 10 . Define the relations R 1 and R 2 on P S as A R 1 B if A ∩ B c ∪ B ∩ A c = ϕ and A R 2 B if A ∪ B c = B ∪ A c , ∀ A , B ∈ P S . Then :
Options
- Aboth R 1 and R 2 are equivalence relations
- Bonly R 1 is an equivalence relation
- Conly R 2 is an equivalence relation
- Dboth R 1 and R 2 are not equivalence relations
Correct answer
A. both R 1 and R 2 are equivalence relations
Step-by-step solution
Given, S = 1 , 2 , 3 , … … 10 P S = power set of S A R 1 B ⇒ A ∩ B c ∪ A c ∩ B = ϕ Now for reflexive property, replacing B with A we get, A ∩ A c ∪ A c ∩ A which ϕ always, Now checking symmetric we will interchange A   &   B , So, B ∩ A c ∪ B c ∩ A which is same as A ∩ B c ∪ A c ∩ B , hence the relation is symmetric, So, R 1 is reflexive, symmetric Now checking for transitive A ∩ B c ∪ A c &