Let A = [1, 2, 3, 5], B = [4, 6, 9] and R be a relation from A to B defined by R = {(x, y) :
Question:

Let A = [1, 2, 3, 5], B = [4, 6, 9] and R be a relation from A to B defined by R = {(xy) : x − y is odd}. Write R in roster form.

Solution:

Given:

A = {1, 2, 3, 5} and B = {4, 6, 9}

R = {(xy) : x − y is odd}

Since $1-4=-3$ is odd, we have:

$1-6=-5$ is odd

$2-9=-7$ is odd

$3-4=-1$ is odd

$3-6=-3$ is odd

$5-4=1$ is odd

$5-6=-1$ is odd

∴ R = {(1,4),(1,6),(2,9),(3,4),(3,6),(5,4),(5,6)}