FUN005 · Functions & graphs · Classes 9–12
Constant Function
A constant function gives the same output for every input. Its graph is a horizontal line, with slope 0.
y = kConstant Function
📐 Formula
f(x) = k; range = {k}
✏️ Worked example
f(x) = 2: f(−5) = f(0) = f(100) = 2.
🌍 Where it is used
A fixed monthly fee or a flat delivery charge.
❓ Quick check
The slope of y = 5 is…
🏋️ Practice
EasyIf f(x) = −3, what is f(10)?
Answer: −3
MediumWhat is the range of f(x) = 4?
Answer: {4}
ChallengeIs a vertical line a constant function? Why?
Answer: No; one x gives many y values