ACT Preparation / Unit 10 ACT 0902 short lesson, about 20 seconds
Function Notation
Captions available
The idea
In f(x), f names the function and x is the input; f(a) is the output when the input is a. Evaluating means replacing x everywhere with a.
In practice
f(x) = x² − 3x: f(4) = 16 − 12 = 4; f(−2) = 4 + 6 = 10.
Where people slip
f(x) is not f times x. Wrap a negative input in parentheses.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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