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Flip to reveal answersWhat does f(x) mean?
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All 10 Flashcards — Function notation
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Question
What does f(x) mean?
Answer
The output of function f for input x. f(3) means substitute x = 3 into the rule.
Question
Is f(x) the same as f × x?
Answer
No — it's 'f of x', the function applied to x. The brackets hold the input.
Question
What makes a rule a function?
Answer
Each input gives exactly ONE output. (Different inputs may share an output.)
Question
How do you evaluate f(a)?
Answer
Replace every x with a (in brackets for negatives/expressions), then simplify.
Question
Evaluate g(x) = x² − 4x at x = −3.
Answer
(−3)² − 4(−3) = 9 + 12 = 21.
Question
How do you solve f(x) = k?
Answer
Set the rule equal to k and solve for x (output → input).
Question
Can two inputs give the same output?
Answer
Yes — e.g. f(x) = x² gives f(2) = f(−2) = 4. So f(x) = k may have several solutions.
Question
How do you read f(a) off a graph?
Answer
Go up from x = a to the curve, then across to the y-axis.
Question
How do you solve f(x) = k off a graph?
Answer
Read across from y = k to the curve, then down to the x-axis (there may be several x).
Question
Find f(2a) for f(x) = 3x − 5.
Answer
Substitute the whole expression: 3(2a) − 5 = 6a − 5.
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Full study notes for Function notation
Topic 2.2 hub
Functions, domain & range
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Math AA SL exam skills
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