Question

please anyone Answer me this question of 11th class of maths ​

Answer 1

Answer:

12) To prove: A⊆ϕ⇔A=ϕ

Proof:

Let:

A⊆ϕ

If A is a subset of an empty set, then A is the empty set.

∴ A=ϕ

Now, let A=ϕ.

This means that A is an empty set.

We know that every set is a subset of itself.

∴ A⊆ϕ

Thus, we have:

A⊆ϕ⇔A=ϕ