1. Algebra 1
Section 4.5

2. Definition
A disjunction is a compound sentence consisting of mathematical statements connected by the word or.

3. Disjunctions
In order for a disjunction to be true, only one of the statements must be true.
The union—the values that are in both solutions—forms the solution to the disjunction.

4. Graph the solution set of
Example 1
Graph the solution set of
x < -4 or x > 1.

5. The symbol often used for or is .
Disjunctions
The symbol often used for or is .
Disjunctions, unlike conjunctions, cannot be written as combined statements.

6. Example 2
x < 4  x ≤ 2

7. Example 3
3x + 4 > 16 or -5x ≤ 20
3x > 12
x > 4
x ≥ -4

8. The solution is all real numbers.
Example 4
3x – 6 ≤ 12  5x > -25
3x ≤ 18
x ≤ 6
x ≥ -5
The solution is all real numbers.

9. Homework: pp