Let S be a relation on the set R of all real numbers defined by S = {(a, b) R × R : a2 + b2 = 1}. Prove that S is not an equivalence relation on R.

S = {(a, b) : a2 + b2 =1}

Proof :


To prove that relation is not equivalence, we need to prove that it is either not reflexive, or not symmetric or not transitive.


Reflexivity : For Reflexivity, we need to prove that-


(a, a) R


Let a = 1/2, a R


Then,



(a, a) S


S is not reflexive


Hence, S is not an equivalence relation on R.


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