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Let A be the set of all human beings in a town at a particular time. Determine whether the following relation is reflexive, symmetric and transitive: R = {(x, y) : x is father of y}

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प्रश्न

Let A be the set of all human beings in a town at a particular time. Determine whether the following relation is reflexive, symmetric and transitive:

R = {(x, y) : x is father of y}

योग
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उत्तर

(i) Reflexivity:

Let x be an arbitrary element of R.

Then, x is father of x cannot be true since no one can be father of himself.

So, R is not a reflexive relation.

(ii) Symmetric: 

Let (x, y) ∈ R

⇒ x is father of y.

⇒ y is son/daughter of x.

⇒ (y, x) ∉ R 

So, R is not a symmetric relation.

(iii) Transitivity:

Let (x, y) ∈ R and (y, z) ∈ R.

Then, x is father of y and y is father of z.

⇒ x is grandfather of z.

⇒ (x, z) ∉ R

So, R is not a transitive relation.

Hence, R is not reflexive, not symmetric and not transitive.

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अध्याय 1: Relations and Functions - EXERCISE 1.1 [पृष्ठ ५]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
अध्याय 1 Relations and Functions
EXERCISE 1.1 | Q 1. (v). (e) | पृष्ठ ५
आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
अध्याय 1 Relations
Exercise 1.1 | Q 1.4 | पृष्ठ १०

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