Math Problem Statement

Let A = {1, {∅}, {1, ∅}}. Consider the following statements: a) {∅}, {1, ∅} ∈ A b) {∅}, {1, ∅} ⊆ A c) {{∅}, {1, ∅}} ⊆ A d) {1, ∅} ⊆ A e) {{1}, {∅}} ⊆ A Which of the following are correct?

Solution

We are given that the set A={1,{},{1,}}A = \{1, \{\emptyset\}, \{1, \emptyset\}\}. Now, let's evaluate each of the statements:

  1. Statement (a): {},{1,}A\{\emptyset\}, \{1, \emptyset\} \in A

    • AA contains the element {}\{\emptyset\} and {1,}\{1, \emptyset\}.
    • Hence, both {}\{\emptyset\} and {1,}\{1, \emptyset\} are elements of AA, making statement (a) true.
  2. Statement (b): {},{1,}A\{\emptyset\}, \{1, \emptyset\} \subseteq A

    • For this to be true, each element of the set {},{1,}\{\emptyset\}, \{1, \emptyset\} must be an element of AA.
    • Both {}\{\emptyset\} and {1,}\{1, \emptyset\} are elements of AA, so this is true.
  3. Statement (c): {{},{1,}}A\{\{\emptyset\}, \{1, \emptyset\}\} \subseteq A

    • This statement claims that the set {{},{1,}}\{\{\emptyset\}, \{1, \emptyset\}\} is a subset of AA.
    • For it to be true, each element of {{},{1,}}\{\{\emptyset\}, \{1, \emptyset\}\} must be an element of AA.
    • Both {}\{\emptyset\} and {1,}\{1, \emptyset\} are elements of AA, so this is true.
  4. Statement (d): {1,}A\{1, \emptyset\} \subseteq A

    • The set {1,}\{1, \emptyset\} is a subset of AA if both 1 and \emptyset are elements of AA.
    • The element 1 is in AA, but \emptyset is not an element of AA; hence, this statement is false.
  5. Statement (e): {{1},{}}A\{\{1\}, \{\emptyset\}\} \subseteq A

    • This statement claims that the set {{1},{}}\{\{1\}, \{\emptyset\}\} is a subset of AA.
    • The set {1}\{1\} is not an element of AA, but {}\{\emptyset\} is. Therefore, this statement is false.

Conclusion:

The correct statements are (a), (b), and (c), so the correct answer is:

D) a and c


Would you like more details on this solution or any further clarification?

Here are 5 related questions for further practice:

  1. What is the difference between an element of a set and a subset?
  2. How would the answer change if \emptyset were an element of AA?
  3. What does it mean for a set to be a subset of another set?
  4. How would you represent the power set of AA?
  5. Can a set contain both elements and subsets simultaneously?

Tip: When evaluating membership (\in) and subset (\subseteq) relationships, always carefully distinguish between sets and their elements.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Set Membership
Subset Relations

Formulas

-

Theorems

Subset Definition
Membership Definition

Suitable Grade Level

Grades 11-12