Q.

If a relation R is defined from a set A = {2, 3, 4, 5} to a set B = {3, 6, 7, 10} as follows (x,y)∈R⇔x divides y. Expression of R-1 is represented by

1 {(6, 2), (10, 2), (3, 3), (6, 3)}  
2 {(6, 2), (3, 3), (10, 5), (10, 2)}  
3 {(6, 2), (10, 2), (3, 3), (6, 3), (10, 5)}  
4 None of these  

Ans.

(3)

Recall that a∣b stands for a divides b. For the elements of the given sets A and B, we find 2∣6, 2∣10, 3∣3, 3∣6, 5∣10

⇒  R={(2,6),(2,10),(3,3),(3,6),(5,10)}

∴  R-1={(6,2),(10,2),(3,3),(6,3),(10,5)}