Exercise · ZW-SUBSET-001 · ★☆☆ Basic

If A = {1,2} and B = {1,2,3}, which relation is true?

Choose one option.

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  • D. A ⊆ B

Explanation

A = {1,2} ⊆ B = {1,2,3} because 1 and 2 are in B. B ⊆ A is false (3 is not in A), A is not empty and 3 ∈ A is also false.

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Review the concept: Subset

A set A is a subset of B when every element of A also belongs to B.

\[A \subseteq B \Longleftrightarrow \forall x\,(x\in A \Rightarrow x\in B)\]

More practice problems: subset

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