Question

The relation \( R = \{(x, y) : x, y \in \mathbb{Z} \text{ and } x + y \text{ is even} \} \) is: 

• A. reflexive and transitive but not symmetric
• B. reflexive and symmetric but not transitive
• C. symmetric and transitive but not reflexive
• D. an equivalence relation

Hint:

When dealing with relations, always verify the properties of reflexivity, symmetry, and transitivity to determine equivalence.

Answer 1

The Correct Option is D

To determine whether the relation is an equivalence relation, we check if it is reflexive, symmetric, and transitive. 

Step 1: Check if the relation is reflexive by checking if \( x + x \) is even for all integers \( x \). 

Step 2: Check if the relation is symmetric by ensuring if \( x + y \) is even, then \( y + x \) is also even. 

Step 3: Check if the relation is transitive by verifying that if \( x + y \) and \( y + z \) are even, then \( x + z \) is also even. 

Final Conclusion: The relation is an equivalence relation, which is Option 4.