Domain, Range & Behavior
Domain is the allowed inputs. Range is the possible outputs.
The rules
- Exclude values that make a denominator zero.
- Exclude values that make the inside of an even root negative.
- Use end behavior: a positive leading coefficient on an even-degree polynomial opens upward.
- Read range from the lowest and highest y-values on a graph.
Watch out: Forgetting the denominator restriction.
Worked example
What is the domain of f(x) = √(x − 2)?
- The inside of the root must be at least 0.
- x − 2 ≥ 0 gives x ≥ 2.
Answer: x ≥ 2
Try it yourself
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