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Questions and Answers
What is a relation from a set A to a set B?
What is a relation from a set A to a set B?
What is the domain of a relation?
What is the domain of a relation?
What is the range of a relation?
What is the range of a relation?
What is a function from a set A to a set B?
What is a function from a set A to a set B?
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What is the domain of a function?
What is the domain of a function?
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What is the codomain of a function?
What is the codomain of a function?
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What is an one-one function?
What is an one-one function?
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What is an onto function?
What is an onto function?
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What is a bijective function?
What is a bijective function?
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What is the range of a function?
What is the range of a function?
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Study Notes
Relations and Functions
Relations
- A relation from a set A to a set B is a subset of A × B.
- It can be represented as:
- R = {(a, b) | a ∈ A, b ∈ B, and a is related to b}
- Example: Let A = {1, 2, 3} and B = {4, 5}. Then, {(1, 4), (2, 5), (3, 4)} is a relation from A to B.
- Domain of a relation: The set of all first elements of the ordered pairs in the relation.
- Range of a relation: The set of all second elements of the ordered pairs in the relation.
Functions
- A function is a relation from a set A to a set B such that:
- Every element of A is related to exactly one element of B.
- A function is denoted as f: A → B, where f is the function and A and B are the domain and codomain respectively.
- Domain of a function: The set of all elements in A.
- Range of a function: The set of all elements in B that are related to some element in A.
- Codomain of a function: The set of all elements in B.
Types of Functions
- One-One Function (Injective): A function is one-one if different elements of the domain have different images in the codomain.
- Onto Function (Surjective): A function is onto if every element of the codomain is the image of some element in the domain.
- One-One Correspondence (Bijective): A function is bijective if it is both one-one and onto.
Inverse of a Function
- If f: A → B is a bijective function, then there exists a function g: B → A such that:
- f(g(b)) = b for all b ∈ B
- g(f(a)) = a for all a ∈ A
- The function g is called the inverse of f, denoted as f^(-1).
Composite Functions
- If f: A → B and g: B → C are two functions, then the composite function gof: A → C is defined as:
- (gof)(a) = g(f(a)) for all a ∈ A
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Description
Test your knowledge of relations and functions, including domain, range, and types of functions such as one-one, onto, and bijective functions. Learn about inverse and composite functions too!