Let and ' ' be an equivalence relation on , defined by , if and only if . Then the number of ordered pairs which satisfy this equivalence relation with ordered pair is equal to :
- (A)6
- (B)5
- (C)8
- (D)7✓ Correct
Answer: (D)
Solution
The relation means , that is , so for a positive integer . Both entries must lie in , and forces , while every keeps within range. The pairs are
so the number of ordered pairs related to is .
so the number of ordered pairs related to is .
JEE Main · 2021 · 16 Mar 2021 · Shift 2 · Single correct option