CLASS-8
RELATION & MAPPING - RELATION IN ROSTER FORM

Express the following relations in the roster form –

Example.1)

The matching pairs are (1, 1), (27, 3), (64, 4), (125, 5)

So, the relation R = {(1, 1), (27, 3), (64, 4), (125, 5)} is from the set,

A = {1, 27, 64, 125} to the set B = {4, 1, 5, 3}, Also in each pair the first element “is the cube of” the second elements.

We write – 1 R 1, 27 R 3, 64 R 4, 125 R 5

And,  R = {(a, b) : a Є A, b Є B and a = bᶟ}

Example.2)

The matching pairs are (Rome, Italy), (Tehran, Iran), (Beijing, Chaina), (Lisbon, Portugal)

So, the relationis R = {(Rome, Italy), (Tehran, Iran), ( Beijing, Chaina), (Lisbon, Portugal)},

From the set A = {Rome, Tehran, Beijing, Lisbon} and  B = {Chaina, Italy, Portugal, Iran}

And, it can be described as “ is the capital of ”

We can also write Rome R Italy,  Tehran  R  Iran,  Beijing  R  China,  Lisbon  R  Portugal

And  R = {(a, b) : a Є A, b Є B and a is the capital of b }