1.

Let * be a binary operation on N, N being set of natural number defined by a * b = ab for all a, b ∈ N. Verify * is associative and commutative on N.

Answer»

Given , binary operation is a * b = ab

Let, 2, 3 ∈ N

So, 2 * 3 = 23 = 8 and 3 * 2 = 32 = 9 

2 * 3 ≠ 3 * 2

So, '*' is not commutative on N

Also, 2 * (2 * 3) = 2 * 23 = 2 * 8 = 28 = 256

and (2 * 2) * 3 = 22 * 3 = 4 * 3 = 43 = 64

So, 2 * (2 * 3) ≠ (2 * 2) * 3

So, '*' is not associative on N



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