ACT Preparation / Unit 10 ACT 0907 short lesson, about 20 seconds
Domain
Captions available
The idea
The domain is the set of allowed inputs. Exclude inputs that divide by zero or take an even root of a negative, and any the situation rules out.
In practice
f(x) = 1/(x − 4) excludes 4; g(x) = √(x + 2) needs x ≥ −2.
Where people slip
In context, the domain shrinks: a number of tickets cannot be negative or fractional.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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