1.

Define a Cartesian product of two sets.

Answer»

Let A and B two non-empty sets. Then, the Cartesian product of A and B is the set denoted by Ax B, consisting of all ordered pairs (a, b) such that a e A and be B.

A x B= {(a, b): a ∈ A, b∈B} 

Keen Eye: 

  • If n(A) = p and n(B) = q, then n (A x B) = pq and n (B x A) = pq 
  •  If at least one of A and B is infinite then AxB is infinite and B x A is infinite, 
  • In general, A x B ≠ B x A 
  • A x A x A = {(a, b, c) : a, b, c ∈A}. Here (a, b, c) is called an ordered triplet.


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