The relation R on set A={1, 2, 3, 4, 5}, given by R={(a, b) : |A-b| is even} is :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Equivalence
$A=\{1, 2, 3, 4, 5\}$
$R=|a-b|$ is even
→ for $∀a∈A$ $|a-a|=0$ (always even)
so $(a,a)∈R$ ⇒ Reflexive relation
→ for $(a,b)∈R$
$|(a-b)|$= Even
so $|a-b|=|b-a|$ is even
so $(b,a)∈R$ ⇒ Symmetric relation
→ for $(a,b)∈R,(b,c)∈R$
if (a, b) both are odd ⇒ b, c both are odd and if a, b are both even ⇒ b, c both are even
$⇒ |a - c|$ is even so $(a,c)∈R$ ⇒ Transitive relation
⇒ Equivalence relation