Let be the set of natural numbers and be the relation on defined by iff for all . Show that is an equivalence relation.
Answer: is an equivalence relation.
Solution
Reflexive: needs , which is always true. So is reflexive.
Symmetric: if then , i.e. , which is exactly . So is symmetric.
Transitive: let and , so and .
Multiply the two equations: , i.e. . Cancelling (non-zero in ) gives
Symmetric: if then , i.e. , which is exactly . So is symmetric.
Transitive: let and , so and .
Multiply the two equations: , i.e. . Cancelling (non-zero in ) gives
CBSE Class 12 Board · 2020 · Subjective