Question

If a set $A$ is a subset of another set $B,$ then , which means

• A. $A\subseteq B$
• B. $B\supseteq A$
• C. $\mathrm{if}a\in A\Rightarrow a\in B$
• D. $\mathrm{if}a\in B\Rightarrow a\in A$

Answer 1

Answer: (A), (C)

$\mathrm{if}a\in A\Rightarrow a\in B$

Given a set $A$ is a subset of another set $B.$

This means each and every element of a set $A$ is also an element of another set $B.$

According to the notation, we can write it as $A\subseteq B.$
$\Rightarrow \text{if}a\in A\Rightarrow a\in B.$