Question:
An integer m is said to be related to another integer n if m is a multiple of n.Check if the relation is symmetric, reflexive and transitive.
Solution:
$R=\{(m, n): m, n \in Z, m=k n$, where $k \in N\}$
Reflexivity :
Let $m$ be an arbitrary element of $R$. Then,
$m=k m$ is true for $k=1$
$\Rightarrow(m, m) \in R$
Thus, $R$ is reflexive.
Symmetry : Let $(m, n) \in R$
$\Rightarrow m=k n$ for some $k \in N$
$\rightarrow n=\frac{1}{k} m$
$\Rightarrow(n, m) \notin R$
Thus, $R$ is not symmetric.
Transitivity : Let $(m, n)$ and $(n, o) \in R$
$\Rightarrow m=k n$ and $n=l o$ for some $k, l \in N$
$\Rightarrow m=(k l) o$
Here, $k l \in R$
$\Rightarrow(m, o) \in R$
Thus, $R$ is transitive.