Question

The relation $R$ is defined on the set of natural numbers as $\{(a$, $b)$ : $a = 2b\}$. Then, $R^{-1}$ is given by

• A. $\{(2$, $1)$, $(4$, $2)$, $(6$, $3)$, $\ldots \}$
• B. $\{(1$, $2)$, $(2$, $4)$, $(3$, $6)$, $\ldots \}$
• C. $R^{-1}$ is not defined
• D. None of these

Answer 1

Answer: (B)

$R = \{(2$, $1)$, $(4$, $2)$, $(6$, $3)\ldots\}$
So, $R^{-1} = \{(1$, $2)$, $(2$, $4)$, $(3$, $6)$,$\ldots\}$