Example 45 Determine which of the following binary operations on the set R are associative and which are commutative. (a) a * b = 1 ∀ a, b ∈ R Check commutative * is commutative if a * b = b * a Since a * b = b * a ∀ a, b ∈ R * is commutative a * b = 1 Check associative * is associative if a (a * b) * c = a * (b * c) Since (a * b) * c = a * (b * c) ∀ a, b, c ∈ R * is an associative binary operation Check associative * is associative if a (a * b) * c = a * (b * c) Since (a * b) * c = a * (b * c) ∀ a, b, c ∈ R * is an associative binary operation a * (b * c) = a * 1 = 1

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.

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