Types of Functions: Definition, Classification and Examples

ElevatEd
Math
June 25, 2024

The fundamental building block of mathematics, functions are essential to many academic fields and real-world applications. A function delineates a certain correlation between inputs, commonly referred to as the domain, and outputs, commonly referred to as the range. To assist you grasp the unique nature of functions, we will examine several function types, their classifications, and examples in this blog.

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What is a Function?

A function f is defined as follows in mathematics: f: A→B is the relation between a set of inputs (A) and a set of outputs (B). There is precisely one element in the range B for every element in the domain 𝐴 A. Usually, this connection is expressed as y=f(x), where x is the input and y is the corresponding output.

Classification of Functions

Based on their characteristics and actions, functions can be categorized in a number of ways. The following are a few of the main categories:

Based on the Nature of the Function

Linear Functions: These are functions of the form f(x)=mx+b, where m is the slope and b is the y-intercept. The graph of a linear function is a straight line.

Example: 3f(x)=2x+3

Quadratic Functions: These are functions of the form f(x)=ax 2 +bx+c, where a, b, and c are constants. The graph of a quadratic function is a parabola.

Example: f(x)=−4x+4

Polynomial Functions: These involve terms with non-negative integer exponents. A general polynomial function can be written as f(x)=+a +⋯+x+a.

Example: f(x)=4 +3 −2x+1

Rational Functions: Ratios of two polynomials are known as rational functions.

Example: f(x)=

Exponential Functions: Functions of the type f(x)= are known as exponential functions. In this case, a represents the constant and x is the exponent.

For instance, V(x)=

Logarithmic functions:

They are the inverses of exponential functions, represented by the formula f(x)=
Example: f(x)=

Based on the Behavior of the Function

Even Functions: A function f(x) is even if f(−x)=f(x) for all x in the domain. The graph is symmetric about the y-axis.

Example: f(x)=

Odd Functions: A function f(x) is odd if f(−x)=−f(x) for all x in the domain. The graph is symmetric about the origin.

Example: f(x)=

Periodic Functions: A function f(x) is periodic if there exists a positive constant p such that f(x+p)=f(x) for all x in the domain.

Example: f(x)=sin(x), with a period of 2π

Based on Continuity

Continuous Functions: If a function f(x) has no breaks, leaps, or holes in its graph, it is considered continuous.
For instance, f(x)=
Discontinuous Functions: Functions that are not continuous at least once are known as discontinuous functions.
For instance, f(x)= x 1 is discontinuous at 0.

Based on Injectivity and Surjectivity

Injective Functions: The concept of injective functions (one-to-one) states that a function f is injective if and only if f(a)=f(b) implies a=b.
For example, f(x)=2x+3
Surjective Functions (Onto): If every element in the range B has a preimage in the domain A, then a function f is surjective.
For instance, when analyzed across the domain of non-negative real numbers, f(x)=
Bijective Functions: If a function is both surjective and injective, it is said to be bijective.
For instance, f(x)=x+1 across all real numbers is equal to f(x) + 1.

Examples of Different Types of Functions

Example of a Linear Function
f(x)=3x+2

Graph: A line with a slope of three and a y-intercept 2.

Example of a Quadratic Function
f(x)=−4x+4

Graph: A rising parabola with a vertex at (2, 0).

Example of an Exponential Function
f(x) =

Graph: A quickly rising curve that begins at (0,1) .

Example of a Logarithmic Function:
f(x) =

Graph: A rising curve that goes through (1, 0) (1, 0).

Example of a Rational Function
f(x) =

Graph: The graph displays a hyperbola with two asymptotes

In order to get deeper into mathematical theory and applications, it is essential to comprehend the various function types and their classifications. Different kinds of functions can be used to address a variety of mathematical and practical issues because of their distinctive characteristics and behaviors. Gaining a solid understanding of these foundational ideas will prepare you to take on more challenging math subjects.

FAQs (Frequently Asked Questions)

Q1: What is a function in mathematics?

Ans: A function in mathematics is a relation between a set of inputs (domain) and a set of possible outputs (range), where each input is related to exactly one output. It is typically written as y=f(x)y = f(x)y=f(x), where xxx is an input and yyy is the corresponding output.

Q2: How are functions classified?

Ans: Functions can be classified based on various criteria such as their nature, behavior, continuity, and injectivity/surjectivity. The main classifications include:

1. Based on the nature of the function: Linear, Quadratic, Polynomial, Rational, Exponential, and Logarithmic.
2. Based on the behavior of the function: Even, Odd, Periodic.
3. Based on continuity: Continuous, Discontinuous.
4. Based on injectivity and surjectivity: Injective (One-to-One), Surjective (Onto), Bijective (Both injective and surjective).

Q3: What is a linear function?

Ans: A linear function is a function of form f(x)=mx+bf(x) = mx + bf(x)=mx+b, where mmm is the slope and bbb is the y-intercept. The graph of a linear function is a straight line. An example is f(x)=2x+3f(x) = 2x + 3f(x)=2x+3.

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