Let $R=\left\{(a, b): a=b^{2}\right\}$ for $a l l a, b \in N$.
Show that R satisfies none of reflexivity, symmetry and transitivity.
We have, $R=\left\{(a, b): a=b^{2}\right\}$ relation defined on $N$.
Now,
We observe that, any element a $\in \mathrm{N}$ cannot be equal to its square except 1 .
$\Rightarrow(a, a) \notin R \forall a \in N$
For e.g. $(2,2) \notin R \because 2 \neq 2^{2}$
$\Rightarrow \mathrm{R}$ is not reflexive.
Let $(a, b) \in R \forall a, b \in N$
$\Rightarrow a=b^{2}$
But b cannot be equal to square of $a$ if $a$ is equal to square of $b$.
$\Rightarrow(b, a) \notin R$
For e.g., we observe that $(4,2) \in R$ i.e $4=2^{2}$ but $2 \neq 4^{2} \Rightarrow(2,4) \notin R$
$\Rightarrow \mathrm{R}$ is not symmetric
Let $(a, b) \in R$ and $(b, c) \in R \forall a, b, c \in N$
$\Rightarrow \mathrm{a}=\mathrm{b}^{2}$ and $\mathrm{b}=\mathrm{c}^{2}$
$\Rightarrow \mathrm{a} \neq \mathrm{c}^{2}$
$\Rightarrow(\mathrm{a}, \mathrm{c}) \notin \mathrm{R}$
For e.g., we observe that
$(16,4) \in R \Rightarrow 16=4^{2}$ and $(4,2) \in R \Rightarrow 4=2^{2}$
But $16 \neq 2^{2}$
$\Rightarrow(16,2) \notin \mathrm{R}$
$\Rightarrow \mathrm{R}$ is not transitive.
Thus, $R$ is neither reflexive nor symmetric nor transitive.