Let S be the set of all real numbers and let R be a relation on S, def...
(i) |a – a| = 0
< 1 is always true
(ii) a R b ⇒ |a – b|
< 1 ⇒ |-(a – b)|
< ⇒ |b – a|
< 1 ⇒ b R a.
(iii) 2R 1 and
But, 2 is not related to 1/2. So, R is not transitive.
View all questions of this test
Let S be the set of all real numbers and let R be a relation on S, def...
aRb <=> 1+ab >0
a. is reflexive because a*a for any real number except 0 will be positive hence >0, and if a=0 then a*a + 1 >0.
b. if a*b + 1 > 0 then b*a + 1 will also be > 0, hence symmetric.
c. a=-2 b=0, -2*0 + 1 >0, ab+1 > 0
b=0, and if c=4 then 0*4 + 1 > 0
but a is not related to c, because a=-2, c=4, and -2*4 + 1 < 0
Hence, the given relation is reflexive and symmetric but not transitive.
Let S be the set of all real numbers and let R be a relation on S, def...
Explanation:
To determine whether the relation R defined on the set of real numbers S is reflexive, symmetric, and transitive, we need to analyze each property individually.
Reflexive:
A relation R is reflexive if every element a in S is related to itself, i.e., a R a. In this case, for any real number a, |a - a| = 0 which is not greater than 1. Therefore, the relation R is reflexive.
Symmetric:
A relation R is symmetric if for every pair of elements a and b in S, if a R b, then b R a. In this case, if |a - b| is less than or equal to 1, then it follows that |b - a| is also less than or equal to 1. Therefore, the relation R is symmetric.
Transitive:
A relation R is transitive if for every triple of elements a, b, and c in S, if a R b and b R c, then a R c. In this case, if |a - b| and |b - c| are both less than or equal to 1, it does not necessarily imply that |a - c| is also less than or equal to 1. Consider the example where a = 0, b = 0.5, and c = 1. Here, |a - b| = 0.5 and |b - c| = 0.5, both of which are less than or equal to 1. However, |a - c| = 1, which is greater than 1. Therefore, the relation R is not transitive.
Conclusion:
Based on the analysis of the properties, the relation R is reflexive and symmetric but not transitive. Therefore, the correct answer is option 'A' - reflexive and symmetric but not transitive.
Additional Information:
An equivalence relation is a relation that is reflexive, symmetric, and transitive. Since the relation R defined in this case is not transitive, it does not satisfy all the properties required for an equivalence relation. Hence, the relation R is not an equivalence relation.