Q.

Let A = {2, 3, 4} and B = {8, 9, 12}. Then the number of elements in the relation

R={((a1,b1),(a2,b2))(A×B,A×B):a1 divides b2 and a2 divides b1} is                   [2023]

1 24  
2 12   
3 36   
4 18  

Ans.

(3)

a1 divides b2

Each element has 2 choices. 

3×2=6

a2 divides b1 

Each element has 2 choices. 

3×2=6

Total number of relations is 6×6=36