What's a domain?
The set of inputs the function ACCEPTS. Cambridge usually states it, or expects you to find it from the formula.
The domain of a function is the set of all input values for which is defined.
Common natural domains:
- Polynomials (): domain is ALL real numbers .
- Rational functions (): exclude any that makes the denominator zero. Here .
- Square root: : need , so .
- Logarithms: : .
Cambridge often gives a RESTRICTED domain like for — i.e. only that piece of the parabola.
Notation. Domain stated as an inequality or interval: means .
- Domain = allowed inputs.
- Polynomial: all reals.
- Rational: exclude zeros of the denominator.
- Square root: argument .