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Let Z={a,c,{a,b}}. What is |Z|?

What is the power set of Z?

Which of the following are true?

1. {a,c} ⊆ Z

2. a ∈ Z

3. {c} ⊆ Z

4. {c} ∈ Z

5. b ∈ Z

6. {a,b} ∈ Z

1 Answer

3 votes


Z=\{a,c,\{a,b\}\}


\boxedZ (treat
\{a,b\} as one element of
Z)

The power set of
Z is


\boxed{2^Z=\bigg\{\{\},\{a\},\{c\},\big\{\{a,b\}\big\},\{a,c\},\big\{a,\{a,b\}\big\},\big\{c,\{a,b\}\big\},\big\{a,c,\{a,b\}\big\}\bigg\}}

1.
\{a,c\}\subseteq Z is true because both
a\in Z and
c\in Z.

2.
a\in Z is true.

3.
\{c\}\subseteq Z is true (same reason as part 1).

4.
\{c\}\in Z is false because
Z does not contain the set
\{c\}, rather just the element
c itself.

5.
b\in Z is false because the element
b on its own simply is not in
Z. That
b\in\{a,b\} does not mean
b\in Z, but that
b belongs to a subset of
Z.

6.
\{a,b\}\in Z is true.

User Petronila
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