← Back to Grade 8 Topics
Functions
Introduction to Functions
A function is a relationship where each input has exactly one output. Key concepts: • Input (x): Independent variable • Output (y or f(x)): Dependent variable • Domain: Set of all possible inputs • Range: Set of all possible outputs Function notation: f(x) = 2x + 3 Read as "f of x equals 2x plus 3" To evaluate: Replace x with the given value Example: If f(x) = 2x + 3, then f(5) = 2(5) + 3 = 13
Example:
Is this a function? {(1,2), (2,4), (3,6), (1,8)} NO! The input 1 has two different outputs (2 and 8). Each input must have exactly one output. Corrected: {(1,2), (2,4), (3,6), (4,8)} ✓