MathIsimple

Function Definitions & Representations

Understand what functions are! Learn function definitions, domain and range, and how to represent functions using formulas, tables, and graphs.

9th Grade
Functions
~60 min
🎮 Interactive Activity: Function Evaluator

Evaluate functions for given inputs!

Function: f(x) =

2x + 3

Find: f(5)

🎮 Interactive Activity: Domain & Range Finder

Identify the domain and range of functions!

Function:

f(x) = 2x + 3
1. What is a Function?

Function Definition

A function is a relation where each input (x-value) has exactly one output (y-value).

Key Property: One Input, One Output

For every x in the domain, there is exactly one y in the range.

Input
x
Function
f
Output
y
Example: Is {(1,2), (2,3), (3,4)} a function?

Step 1: Check each input: 1 → 2, 2 → 3, 3 → 4

Step 2: Each input has exactly one output ✓

Answer: Yes, it is a function!

2. Domain & Range
3. Function Representations
4. Function Notation
Frequently Asked Questions

Practice Time!

Practice Quiz
10
Questions
0
Correct
0%
Score
1
What is a function?
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2
If f(x) = 2x + 3, what is f(5)?
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3
Which relation is NOT a function?
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4
What is the domain of f(x) = 1/(x-2)?
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5
If g(x) = x² - 4, what is g(-3)?
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6
What does the vertical line test determine?
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7
If f(x) = 3x - 1 and f(a) = 8, what is a?
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8
What is the range of f(x) = x²?
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9
Which represents a function?
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10
What is f(0) if f(x) = 5x + 2?
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