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Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b) : b = a + 1} is reflexive, symmetric or transitive.

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Question

Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b) : b = a + 1} is reflexive, symmetric or transitive.

Sum
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Solution

Let A = {1, 2, 3, 4, 5, 6}

A relation R is defined on set A as:

R = {(a, b) : b = a + 1}

∴ R = {(1, 2), (2, 3), (3, 4), (4, 5), (5, 6)}

We can find (a, a) ∉ R, where a ∈ A.

For instance, (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6) ∉ R

∴ R is not reflexive.

It can be observed that (1, 2) ∈ R, but (2, 1) ∉ R.

∴ R is not symmetric.

Now, (1, 2), (2, 3) ∈ R

But, (1, 3) ∉ R

∴ R is not transitive.

Hence, R is neither reflexive, nor symmetric, nor transitive.

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Chapter 1: Relations and Functions - EXERCISE 1.1 [Page 5]

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NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 1 Relations and Functions
EXERCISE 1.1 | Q 3. | Page 5

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