On a set N of all natural numbers is defined the relation R by a R b iff the GCD of a and b is 2, then R is -Maths 9th

1 Answer

Answer :

(c) Symmetric only• Let a ∈N. Then (a, a) ∉R as the GCD of ‘a’ and ‘a’ is ‘a’ not 2. R is not reflexive • Let a, b ∈N. Then, (a, b) ∉R ⇒ GCD of ‘a’ and ‘b’ is 2 ⇒ GCD of ‘b’ and ‘a’ is 2 ⇒ (b, a) ∈R ∴ R is symmetric • Let a, b, c ∈N. Then, (a, b) ∈R and (b, c) ∈ R ⇒ GCD of a and b is 2 and GCD of b and c is 2 \( ot\Rightarrow\) GCD of a and c is 2 R is not transitive For example, let a = 4, b = 10, c = 12 GCD of (4, 10) = 2 GCD of (10, 12) = 2 But GCD of (4, 12) = 4.

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