# Example 44 - Chapter 1 Class 12 Relation and Functions

Last updated at Dec. 8, 2016 by Teachoo

Last updated at Dec. 8, 2016 by Teachoo

Transcript

Example 44 Let f : X Y be a function. Define a relation R in X given by R = {(a, b): f(a) = f(b)}. Examine whether R is an equivalence relation or not. Equivalence relation are Relations which are reflexive, transitive and symmetric. R = {(a, b): f(a) = f(b)} Check reflexive Since f (a) = f (a), (a, a) R, Hence, R is reflexive. Check symmetric If f (a) = f (b), then f (b) = f (a) Hence, (b, a) R. So, if (a, b) R , then (b, a) R. R is symmetric. Check transitive If (a, b) R f(a) = f(b) Also if, (b, c) R f(b) = f(a) From (1) & (2) f(a) = f(c) (a, c) R, If (a, b) R & (b, c) R , then (a, c) R R is transitive. Hence, R is an equivalence relation.

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Chapter 1 Class 12 Relation and Functions

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.