Let `Z`be the setof all integers and `R`be therelation on `Z`defined as `R={(a , b); a , b in Z ,`and `(a-b)`isdivisible by `5.}`. Prove that `R`is anequivalence relation.
A. reflexive
B. reflexive but not symmetric
C. symmetric and transitive
D. an equivalence relation
A. reflexive
B. reflexive but not symmetric
C. symmetric and transitive
D. an equivalence relation
Correct Answer – D
For reflexive :
(a, a)=a-a=0 is divisible by 5.
For symmetric :
If (a-b) is divisible by 5, then b-a=-(a-b) is also divisible by 5.
Thus relation is symmetric.
For transitive
If (a-b) and (b-c) is divisible by 5.
Then (a-c) is also divisible by 5
Thus relation is transitive
`therefore R` is an equivalence relation.