Ordered Pair and Cartesian Products

 Ordered Pair

The combination of numbers or elements in a fixed order in such a way that the first component always represents the x-component and second component always represents the y-component is known as ordered pair. The elements of an ordered pair are always separated by commas and enclosed within round or small brackets. Eg. (1, 2), (p, q), (Sita, Ram) etc.

The x-component is also known as antecedent and y-component is known as consequent.

Equality of ordered pair

The ordered pair (a, b) and (c, d) are said to be equal if their corresponding elements are equal. i.e., the first component ‘a’ should be equal to the first component ‘c’ and the second component ‘b’ and ‘d’ should be equal.

Mathematically, if (a, b) = (c, d), then, a = c and b = d.

Cartesian Product

Let A and B be two non-empty sets. Then the product A × B (read as A cross B) is the set of all ordered pairs in such a way that the first elements are always taken from set A and second elements from set B.

Mathematically,

A × B = {(x, y): x ϵ A and y ϵ B}

Let’s take an example,

A = (1, 2) and B = (3, 4)

Then A × B = {(1, 3), (1, 4), (2, 3), (2, 4)}

This can be represented by an arrow diagram as follows.

    

A × B = {(1, 3), (1, 4), (2, 3), (2, 4)}

It can also be represented by a table.

        

A × B = {(1, 3), (1, 4), (2, 3), (2, 4)}

Similarly, B × A can also be determined in the same way taking elements of set B first and set A second.

Presenting B × A in a table. 

    

B × A = {(3, 1), (3, 2), (4, 1), (4, 2)}

Representing B × A in arrow diagram,

    

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