Definition Of Domain

Domain of a relation is the set of all x-coordinates of the ordered pairs of that relation.

Examples of Domain

Domain of the relation {(3,4), (9,8), (4,5)} is {3, 4, 9}.

Video Examples: How to Figure the Domain & Range of Ordered Pairs : Math Tips
 

Solved Example on Domain

Ques: Find the domain of f(x) = (x + 3)^-1.

Choices:

A. (- ∞, - 3) or (- 3, - ∞)
B. (- 3, 3)
C. (- ∞, - 3) or (3, ∞)
D. (- ∞, ∞)
Correct Answer: A

Solution:

Step 1:f(x) = (x + 3)^-1.
Step 2: 
Step 3: Domain of a function is the set of all possible input values for the function.
Step 4: Observe that the function  is not defined only when x = - 3.
Step 5: So, the domain for this function is (- ∞, - 3) or (- 3, - ∞).

Related Worksheet

• Graphing-Linear-Functions-for-a-Given-Domain-Gr-8