Q.

Let X = R × R. Define a relation R on X as:

(a1,b1)R(a2,b2)b1=b2.

Statement I: R is an equivalence relation.

Statement II: For some (a, b X, the set

S = {(x, y X :(x, y) R (a, b)} represents a line parallel to y = x.

In the light of the above statements, choose the correct answer from the options given below:          [2025]

1 Statement I is true but Statement II is false.  
2 Statement I is false but State II is true.  
3 Both Statement I and Statement II are false.  
4 Both Statement I and Statement II is true.  

Ans.

(1)

Statement I:

Reflexive : (a1,b1)R(a1,b1)b1=b1

   R is reflexive.

Symmetric : (a1,b1)R(a2,b2)b1=b2

                    (a2,b2)R(a1,b1)b2=b1

   R is symmetric.

Transitive : (a1,b1)R(a2,b2)b1=b2

and (a2,b2)R(a3,b3)b2=b3b1=b3

(a1,b1)R(a3,b3)

Hence, relation R is equivalence relation.

  Statement I is true.

For Statement II: (x, y) R (a, b), for some (a,b)Xy=b

So, Statement II is false.