Distributive Laws of Sets

Distributive laws for union and intersection with clear formulas, explanations, and simple examples.

1. What Are the Distributive Laws?

The distributive laws explain how union and intersection interact with each other. They allow one operation to be distributed over the other, similar to how multiplication distributes over addition in arithmetic.

These laws help simplify complex set expressions.

2. Union Distributes Over Intersection

The union of a set with the intersection of two sets is the same as taking the union individually and then intersecting the results.

2.1. Formula

\( A \cup (B \cap C) = (A \cup B) \cap (A \cup C) \)

2.2. Example

If A = {1}, B = {1,2}, C = {1,3}, then:

A \cup (B \cap C) = \{1\}

(A \cup B) \cap (A \cup C) = \{1\}

3. Intersection Distributes Over Union

The intersection of a set with the union of two sets works in a similar way.

3.1. Formula

\( A \cap (B \cup C) = (A \cap B) \cup (A \cap C) \)

3.2. Example

If A = {2,3}, B = {3,4}, C = {3,5}, then:

A \cap (B \cup C) = \{3\}

(A \cap B) \cup (A \cap C) = \{3\}

4. Why Distributive Laws Matter

These laws are essential when simplifying expressions involving both union and intersection. They help rewrite expressions into clearer or more useful forms.

5. Important Points

Things to keep in mind about distributive laws:

5.1. Key Ideas

  • Union can distribute over intersection.
  • Intersection can distribute over union.
  • These laws make complex set expressions easier to manage.
  • They work for all sets A, B, and C.