Question

Write all the subsets of the sets

$\left(i\right)\left\{a\right\}$

$\left(ii\right)\varphi$.

Answer 1

(i) $\left\{a\right\}\Rightarrow$ subsets $=\left\{a\right\},\varphi$

(ii) $\varphi \Rightarrow$ subsets $=\varphi$