Question

The relation $R$ defined on the set of natural numbers as $\{(a, b): a$ differs from $b$ by 3$\}$ is given by

• A. $\{(4,1),(5,2),(6,3), \ldots\}$
• B. $\{(1,3),(2,6),(3,9), \ldots\}$
• C. $\{(1,4),(2,5),(3,6), \ldots\}$
• D. None of these

Answer 1

Answer: (C)

Given, $R=\{(a, b)$ : a differs from $b$ by 3$\}$
$ \because b-a=3$
$\Rightarrow b=a+3$
For, $ a=1, b=4$
$ a=2, b=5 $
$ a-3, b-6$
$... \,\,\,\,\, ... $
$... \,\,\,\,\,... $
$ \therefore R=\{(1,4),(2,5),(3,6) \ldots \ldots\} $