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S is a relation over the set R of all real numbers and it is given by `(a,b) in S ab >= 0.` Then `S` is :A. symmetric and transitive onlyB. reflexive and symmetric onlyC. a partial order relationD. an equivalence relation |
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Answer» Correct Answer - D Reflexivity: For any `a in R`, we have `a^(2)=aa ge0 implies(a,a)in S` Thus, `(a, a) in S` for all `a in R`. So, S is a reflexive relation on R. symmetry: Let `(a, b) in S`. Then, `(a,b)inSimpliesabge0impliesbage0implies(b,a)inS` Thus, `(a, b)inSimplies(b,a)inS" for all a, b"in R`. So, S is a symmetric relation on R. Transitivity: Let `a, b, c in R` such that `(a, b) in S and (b, c) in R` `implies ab ge 0 and bc ge 0` implies a, b, c are of the same sign. `implies ac ge 0` `implies (a, c) in R`. Thus, `(a,b) in S, (b, c) in S implies (a, c) in S`. So, S is a transitive relation on R. Hence, S is an equivalence relation on R. |
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