Relations and Functions
Mathematics in the Modern World
What is a Relation?
• A relation is a set of ordered pairs (x, y)
• Defines a connection between elements of two
sets
• Can be represented as: {(x , y ), (x , y ), ...}
₁ ₁ ₂ ₂
• Example: {(1, 2), (2, 3), (3, 4)}
Real-Life Examples of Relations
• Student and their grades
• Countries and their capitals
• Employees and their salaries
Ways to Represent a Relation
Domain and Range of a Relation
• Domain: All first elements (x-values)
• Range: All second elements (y-values)
• Example: Relation {(1, 2), (2, 3), (3, 4)}
• Domain = {1, 2, 3}, Range = {2, 3, 4}
What is a Function?
• A function is a special type of relation
• Every element in domain maps to exactly one
element in range
• No element in domain has more than one image
in range
Examples of Functions
• f(x) = 2x + 3 → Linear Function
• f(x) = x² → Quadratic Function
• f(x) = √x → Radical Function
Examples of Non-Functions
• {(1, 2), (1, 3), (2, 4)} – Not a function because 1 maps to both 2 and 3
How to Identify a Function?
• Check if any input has more than one output
• Graphically: Use Vertical Line Test
• If any vertical line intersects the graph more than once, it's not a function
Domain and Range in Functions
• Domain: All possible inputs
• Range: All possible outputs
• Example: f(x) = x², Domain: All real numbers, Range: y ≥ 0
Different Representations of Functions
• 1. Equation Form (y = f(x))
• 2. Table of Values
• 3. Mapping Diagram
• 4. Graph
Linear Functions
• Form: y = mx + b
• Graph: Straight line
• Example: y = 2x + 1
Quadratic Functions
• Form: y = ax² + bx + c
• Graph: Parabola
• Example: y = x² + 2x + 1
Polynomial Functions
• Involves terms with x raised to different powers
• Example: f(x) = x³ - 2x² + x - 5
Rational and Exponential Functions
• Rational: f(x) = (x² + 1)/(x - 1)
• Exponential: f(x) = a^x
Special Types of Functions
• One-to-One Function
• Many-to-One Function
• Onto Function
• Into Function
Composite Functions
• Definition: (f g)(x) = f(g(x))
∘
• Example: f(x) = x², g(x) = x + 1
• f(g(x)) = (x + 1)²
Inverse Functions
• If f(x) = y, then f⁻¹(y) = x
• Example: f(x) = 2x + 3 → f⁻¹(x) = (x - 3)/2
Applications of Functions
• Business: Cost and revenue functions
• Science: Speed and distance relations
• Technology: Algorithm performance
Real-Life Example 1
• Temperature conversion: F = (9/5)C + 32
Real-Life Example 2
• Area of a circle as a function of radius: A(r) = πr²
Checking if Relation is a Function
• Method 1: Check for repeated inputs with different outputs
• Method 2: Use the Vertical Line Test
Graphing Functions
• Plot points from a table of values
• Connect the points smoothly for continuous functions
Summary of Key Points
• Relations vs Functions
• Domain and Range
• Types and Representations
• Applications
Practice Problems
• Determine whether the following are functions:
• 1. {(1, 2), (2, 3), (3, 4)}
• 2. {(1, 2), (1, 3), (2, 4)}
• Find domain and range for f(x) = x² - 1
End of Presentation
• Thank you!
• Questions and Discussion

Relations_and_Functions_Detailed. pptx

  • 1.
  • 2.
    What is aRelation? • A relation is a set of ordered pairs (x, y) • Defines a connection between elements of two sets • Can be represented as: {(x , y ), (x , y ), ...} ₁ ₁ ₂ ₂ • Example: {(1, 2), (2, 3), (3, 4)}
  • 3.
    Real-Life Examples ofRelations • Student and their grades • Countries and their capitals • Employees and their salaries
  • 4.
  • 5.
    Domain and Rangeof a Relation • Domain: All first elements (x-values) • Range: All second elements (y-values) • Example: Relation {(1, 2), (2, 3), (3, 4)} • Domain = {1, 2, 3}, Range = {2, 3, 4}
  • 6.
    What is aFunction? • A function is a special type of relation • Every element in domain maps to exactly one element in range • No element in domain has more than one image in range
  • 7.
    Examples of Functions •f(x) = 2x + 3 → Linear Function • f(x) = x² → Quadratic Function • f(x) = √x → Radical Function
  • 8.
    Examples of Non-Functions •{(1, 2), (1, 3), (2, 4)} – Not a function because 1 maps to both 2 and 3
  • 9.
    How to Identifya Function? • Check if any input has more than one output • Graphically: Use Vertical Line Test • If any vertical line intersects the graph more than once, it's not a function
  • 10.
    Domain and Rangein Functions • Domain: All possible inputs • Range: All possible outputs • Example: f(x) = x², Domain: All real numbers, Range: y ≥ 0
  • 11.
    Different Representations ofFunctions • 1. Equation Form (y = f(x)) • 2. Table of Values • 3. Mapping Diagram • 4. Graph
  • 12.
    Linear Functions • Form:y = mx + b • Graph: Straight line • Example: y = 2x + 1
  • 13.
    Quadratic Functions • Form:y = ax² + bx + c • Graph: Parabola • Example: y = x² + 2x + 1
  • 14.
    Polynomial Functions • Involvesterms with x raised to different powers • Example: f(x) = x³ - 2x² + x - 5
  • 15.
    Rational and ExponentialFunctions • Rational: f(x) = (x² + 1)/(x - 1) • Exponential: f(x) = a^x
  • 16.
    Special Types ofFunctions • One-to-One Function • Many-to-One Function • Onto Function • Into Function
  • 17.
    Composite Functions • Definition:(f g)(x) = f(g(x)) ∘ • Example: f(x) = x², g(x) = x + 1 • f(g(x)) = (x + 1)²
  • 18.
    Inverse Functions • Iff(x) = y, then f⁻¹(y) = x • Example: f(x) = 2x + 3 → f⁻¹(x) = (x - 3)/2
  • 19.
    Applications of Functions •Business: Cost and revenue functions • Science: Speed and distance relations • Technology: Algorithm performance
  • 20.
    Real-Life Example 1 •Temperature conversion: F = (9/5)C + 32
  • 21.
    Real-Life Example 2 •Area of a circle as a function of radius: A(r) = πr²
  • 22.
    Checking if Relationis a Function • Method 1: Check for repeated inputs with different outputs • Method 2: Use the Vertical Line Test
  • 23.
    Graphing Functions • Plotpoints from a table of values • Connect the points smoothly for continuous functions
  • 24.
    Summary of KeyPoints • Relations vs Functions • Domain and Range • Types and Representations • Applications
  • 25.
    Practice Problems • Determinewhether the following are functions: • 1. {(1, 2), (2, 3), (3, 4)} • 2. {(1, 2), (1, 3), (2, 4)} • Find domain and range for f(x) = x² - 1
  • 26.
    End of Presentation •Thank you! • Questions and Discussion