| TWO SETS FORMULA: If A, and B are subsets of universal set U, then | |||
| 1. n(A∪B) = n(A) + n(B) - n(A∩B) | |||
| 2. n(A∩B) = n(A) + n(B) - n(A∪B) | |||
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| 4. no(A) = n(A) - n(A∩B) | |||
| 5. no(B) = n(B) - n(A∩B) | |||
| 6. n(A∪B) = no(A) + no(B) + n(A∩B) | |||
| |||
| |||
| 9. Both = n(A∩B) | |||
| 10. At least one = n(A∪B) | |||
| 11. Exactly one = no(A) + no(B) | |||
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| THREE SETS FORMULA: If A, B, and C are subsets of universal set U, then | |||
| 1. n(A∪B∪C) = n(A) + n(B) + n(C) - n(A∩B) - n(B∩C) - n(A∩C) + n(A∩B∩C) | |||
| 2. n(A∩B∩C) = n(A∪B∪C) - n(A) - n(B) - n(C) + n(A∩B) + n(B∩C) + n(A∩C) | |||
| |||
| 4. no(A) = n(A) - n(A∩B) - n(A∩C) + n(A∩B∩C) | |||
| 5. no(B) = n(B) - n(A∩B) - n(B∩C) + n(A∩B∩C) | |||
| 6. no(C) = n(C) - n(A∩C) - n(B∩C) + n(A∩B∩C) | |||
| 7. no(A∩B) = n(A∩B) - n(A∩B∩C) | |||
| 8. no(B∩C) = n(B∩C) - n(A∩B∩C) | |||
| 9. no(A∩C) = n(A∩C) - n(A∩B∩C) | |||
| 10. Exactly two = no(A∩B) + no(B∩C) + no(A∩C) = n(A∩C) | |||
| 11. Exactly one = no(A) + no(B) + no(C) | |||
| 12. At least one = n(A∪B∪C) | |||
| 13. All three = n(A∩B∩C) | |||
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Set theory is a fundamental branch of mathematics that deals with collections of objects, known as sets. Understanding set operations and formulas is crucial for various fields, including logic, computer science, and probability. This comprehensive guide provides a clear and concise list of essential set formulas, explained with examples and illustrated with Venn diagrams, empowering you to master set theory.
What are Sets?
A set is a well-defined collection of distinct objects, called elements or members. Sets can be represented in various ways, including listing their elements within curly braces (e.g., {1, 2, 3}) or using set-builder notation (e.g., {x | x is an even number}).
Essential Set Operations and Formulas:
Union (∪): The union of two sets A and B, denoted by A ∪ B, is the set containing all elements that are in A, in B, or in both.
Intersection (∩): The intersection of two sets A and B, denoted by A ∩ B, is the set containing all elements that are common to both A and B.
Complement (A'): The complement of a set A, denoted by A' or Aᶜ, is the set containing all elements that are not in A, relative to a universal set U.
Difference (A - B): The difference between two sets A and B, denoted by A - B, is the set containing all elements that are in A but not in B.
Subset (⊆): A set A is a subset of set B, denoted by A ⊆ B, if all elements of A are also elements of B.
Proper Subset (⊂): A set A is a proper subset of set B, denoted by A ⊂ B, if A is a subset of B and A is not equal to B.
Power Set (P(A)): The power set of a set A, denoted by P(A), is the set of all subsets of A, including the empty set and A itself.
Key Set Theory Formulas:
Inclusion-Exclusion Principle: For two sets A and B: |A ∪ B| = |A| + |B| - |A ∩ B| (where |S| denotes the number of elements in set S). This principle can be extended to three or more sets.
De Morgan's Laws:
Venn Diagrams: Visualizing Set Operations
Venn diagrams are powerful tools for visualizing set operations and relationships. They use overlapping circles to represent sets, with the overlapping areas representing intersections and the areas outside the circles representing complements.
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Applications of Set Theory:
Set theory has applications in various fields, including:
Conclusion: Mastering Sets for Mathematical and Computational Thinking
Understanding set theory and mastering set formulas is crucial for developing strong mathematical and computational thinking skills. This guide provides a valuable resource for students, teachers, and anyone looking to strengthen their understanding of sets. By mastering these concepts, you'll be well-equipped to tackle a wide range of problems in mathematics, computer science, and other fields.
Call to Action:
Bookmark this page for quick reference and share it with others who might find it helpful. Practice applying these formulas and using Venn diagrams to solve various set theory problems. The more you practice, the more confident you'll become in working with sets!