Relations and Functions
NCERT Class 11 Mathematics Chapter 2: Relations and Functions (Pages 24–42)
Relations and Functions at a Glance
CBSE
Class 11
Mathematics
Mathematics
2
24–42
7 study resources
Relations and Functions is a chapter in the CBSE Class 11 Mathematics syllabus from Mathematics. This chapter hub brings together revision notes, practice questions, worksheets, flashcards, formula sheet to help students learn, practice, and revise Relations and Functions effectively.
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NCERT Class 11 Mathematics Chapter 2: Relations and Functions (Pages 24–42)
CBSE
Class 11
Mathematics
Mathematics
2
24–42
7 study resources
Download the Relations and Functions revision guide with key points, summaries, and quick revision notes for CBSE Class 11 Mathematics.
Key Points
Definition of Ordered Pair
An ordered pair (a, b) signifies a pair where the order matters, crucial in defining relations.
Cartesian Product of Sets
For sets A and B, A × B contains all ordered pairs (a, b) where a ∈ A and b ∈ B, with |A × B| = |A| × |B|.
Relation Definition
A relation from set A to B is any subset of A × B, depicting a specific relationship between elements.
Domain and Range
The domain is all first elements in a relation, while the range consists of all second elements, important for function analysis.
Function Definition
A function is a specific relation where each element of the domain has one unique image in the codomain.
Real-Valued Function
A function is real-valued if its output values are real numbers. Example: f(x) = x².
Types of Functions
Functions can be linear (e.g., f(x) = mx + c), constant, identity, polynomial, etc., with unique properties.
Example of a Function
R = {(1,2), (2,4)} is a function. R = {(1,2), (1,3)} is not as it fails uniqueness.
Polynomial Function Example
f(x) = x² + 2x + 1 is polynomial. For functions like f(x) = 1/x, it's not polynomial if x ≠ 0.
Graph of Functions
Functions can be illustrated with graphs. The graph of f(x) = x² is a parabola opening upwards.
Addition of Functions
If f and g are functions, their sum (f + g)(x) = f(x) + g(x) is also a function, useful for combined effects.
Subtraction of Functions
For functions f and g, (f - g)(x) = f(x) - g(x) gives the difference, essential in calculus.
Multiplication of Functions
The product of functions f and g is defined as (fg)(x) = f(x) * g(x), impacting growth rates.
Division of Functions
The quotient (f/g)(x) is f(x) / g(x), valid when g(x) ≠ 0; it's useful in rational functions.
Types of Relations
Relations can be reflexive, symmetric, or transitive, influencing how we understand their structure.
Number of Relations
For n elements in A and m in B, the total number of relations from A to B is 2^(n*m).
Key Properties of Functions
Each element in the domain maps to one in the range, ensuring no repeated domains in functions.
Modulus Function Definition
Defined as f(x) = |x|, giving the absolute value, crucial for non-negative outputs.
Example of Graph Interpretation
The graph of f(x) = 2x is a straight line indicating linear growth. Understanding graphs aids in function analysis.
Identifying Non-Functions
If an element in the domain has multiple outputs, e.g., f(x) = {x,y}, it fails to be a function.
Practice important questions and exam-style problems from Relations and Functions. These questions cover key topics from the CBSE Class 11 Mathematics syllabus.
How to practice: Start with the questions below to test your understanding of Relations and Functions. Use the revision guide to review concepts you find difficult, then come back and retry the questions for better retention.
What is the Cartesian product of sets A = {1, 2} and B = {x, y}?
If set A = {a, b} and set B = {1, 2, 3}, how many ordered pairs can be formed?
Which of the following defines a relation?
What is the total number of ordered pairs formed by A × B if A = {x, y} and B = {1, 2, 3, 4}?
Which of the following is a valid ordered pair?
If P and Q are two sets, what is P × Q when P = {a} and Q = {}?
If set A has 5 elements and set B has 2 elements, how many ordered pairs can you form?
Identify a common misconception about Cartesian products.
If set A = {1, 2, 3} and set B = {x, y}, what is A × B?
Which of these represents a function from set A to set B?
Which of the following pairs is NOT a valid representation of a Cartesian product?
If A = {red, blue} and B = {circle, square}, what is A × B?
Which characteristic does an ordered pair need to have?
If A = {1, 2} and B = {x, y}, what is A × B?
How many elements are present in the Cartesian product of A = {a, b} and B = {1, 2, 3}?
Which of the following is true about the Cartesian product A × B?
If A = {1, 2, 3} and B = {x, y}, find a specific element of A × B.
For sets A = {a, b} and B = {1, 2}, which of these pairs is NOT in A × B?
Calculate the Cartesian product of B = {1, 2} and A = {a, b, c}. How many pairs will it have?
If P = {x, y, z} and Q = {1, 2}, what is P × Q?
What is the Cartesian product of two empty sets?
Determine the number of pairs in the Cartesian product C = {red, blue} × D = {circle, square, triangle}.
How many elements will the Cartesian product of A = {a, b, c, d} and B = {2, 3} contain?
If E = {x, y} and F = {1, 2, 3, 4}, which of the following represents an element of E × F?
Which statement about the order of elements in ordered pairs is correct?
If A has 4 elements and B has 5 elements, what is the number of pairs in A × B?
Link the situation: if A = {p, q} and B = {r}, how many unique pairs can be formed in A × B?
Given two sets A = {x} and B = {y, z}, what is A × B?
Which of the following is a relation from R to R?
What is the domain of the function f(x) = 1/(x - 2)?
Which of the following is a property of a reflexive relation?
What is the range of the function f(x) = x^2?
If R = {(x, y) : y = 2x + 1}, which of the following points belongs to R?
What type of function is defined by f(x) = |x|?
The relation R = {(a, b) : a - b ∈ Z} is what type of relation?
If two relations R and S are equal, which of the following must always be true?
Find the domain of the function f(x) = √(x - 4).
The graph of f(x) = x^3 is what type of function?
What is the effect of composing two functions f(g(x))?
Which of the following defines a polynomial function?
If f(x) = x^2 and g(x) = 3x + 4, what is (f + g)(x)?
The signum function f(x) gives which of the following outputs?
If R is a relation and it is transitive, which must hold?
What is the definition of an identity function?
Which of the following is true about a constant function?
What is the range of the function f(x) = |x|?
If f(x) = x^2 and g(x) = x + 1, what is (f - g)(x)?
What is the signum function f(x) defined as?
Which operation is used to combine functions f and g where (f g)(x) = f(x)g(x)?
If f(x) = kx, where k is a scalar, what is the form of αf?
Which of the following statements is false regarding the range of a constant function?
For which function is the graph always above the x-axis?
What is the effect of taking the modulus of a negative number?
Find (f + g)(x) if f(x) = 3x and g(x) = -2x.
What is (f / g)(x) for f(x) = x^2 and g(x) = x if g(x) ≠ 0?
Which function's graph passes through the origin and has a slope of 1?
Which operation involves evaluating two functions at the same input and finding their product?
In the modulus function, f(x) = |x|, what happens to negative values of x?
What is the graphical representation of a constant function?
Download and practice Relations and Functions worksheets to improve problem-solving accuracy and speed for CBSE Class 11 Mathematics exams.
This worksheet covers essential long-answer questions to help you build confidence in Relations and Functions from Mathematics for Class 11 (Mathematics).
Questions
Define the Cartesian product of two sets and illustrate with an example. How many ordered pairs can be formed from two sets with m and n elements?
The Cartesian product of two sets A and B, denoted as A × B, is the set of all ordered pairs (a, b) where a ∈ A and b ∈ B. If A has m elements and B has n elements, then the number of ordered pairs is m × n. For example, let A = {1, 2} and B = {a, b, c}. The Cartesian product A × B would be {(1, a), (1, b), (1, c), (2, a), (2, b), (2, c)}, which has 6 ordered pairs (2 × 3 = 6).
Explain what a relation is and its components. How does it differ from a function?
A relation from a set A to a set B is a subset of the Cartesian product A × B. It consists of ordered pairs (a, b) where a ∈ A and b ∈ B. The components of a relation include the domain (set of all first elements) and the range (set of all second elements). A function is a special type of relation where each element in the domain is associated with exactly one element in the codomain. In other words, a function cannot assign the same input to multiple outputs.
What is the domain and range of a given relation R? Provide an example.
For a relation R = {(1, 2), (3, 4), (3, 5)}, the domain is the set of all unique first elements, which is {1, 3}. The range is the set of all unique second elements, which is {2, 4, 5}. Each element in the domain corresponds to its associated values in the range, showcasing the relation between the two sets.
Describe how to determine if a relation is a function with an example.
To determine if a relation is a function, check if each input in the domain relates to one, and only one output in the codomain. For example, in the relation R = {(2, 3), (3, 5)}, each input (2 and 3) maps to a unique output (3 and 5), thus R is a function. Conversely, R = {(1, 2), (1, 3)} is not a function because the input '1' maps to two different outputs.
What are reflexive, symmetric, and transitive relations? Give definitions and examples.
A relation R is reflexive if for every element a in set A, (a, a) ∈ R. Example: In the relation R = {(1, 1), (2, 2)}, it's reflexive. It is symmetric if for any (a, b) in R, (b, a) is also in R. Example: R = {(1, 2), (2, 1)} is symmetric. It is transitive if whenever (a, b) ∈ R and (b, c) ∈ R, then (a, c) ∈ R. Example: If R = {(1, 2), (2, 3)}, then R is transitive because (1, 3) must also belong to R.
Define a function and describe its characteristics. How do you represent a function graphically?
A function is a relation where each input has a unique output, often represented as f: A → B. Characteristics include domain, range, and specific rules for outputs based on inputs. Graphically, functions are represented through curves or lines on a Cartesian plane, where each input value corresponds to exactly one output value, thus passing the vertical line test.
How can you find the image of an element under a function? Illustrate with an example.
To find the image, substitute the input value into the function's rule. For example, if f(x) = 2x + 3, to find the image of x = 2, substitute: f(2) = 2(2) + 3 = 7. The image of 2 is 7. This process exemplifies how functions map inputs to specific outputs.
What is the significance of the range of a function? Describe how to determine it from a function's rule.
The range of a function is the set of all possible output values. To determine the range, analyze the function's rule. For instance, for f(x) = x^2, the output is always non-negative, so the range is [0, ∞). To find the range, consider extreme values of the variable, and ensure all outputs are accounted for.
Illustrate the concept of composite functions with an example. How do we denote a composite function?
A composite function is formed by combining two functions. If f(x) and g(x) are functions, the composite function (f ∘ g)(x) denotes f(g(x)). For example, if f(x) = x + 1 and g(x) = x^2, then (f ∘ g)(x) = f(g(x)) = f(x^2) = x^2 + 1. This shows the message that input x goes through g first, and the result is then input into f.
This worksheet challenges you with deeper, multi-concept long-answer questions from Relations and Functions to prepare for higher-weightage questions in Class 11.
Questions
Explain the concept of Cartesian products of two sets and provide a detailed example involving three elements in the first set and two elements in the second set, illustrating how many ordered pairs can be formed.
Consider sets A = {1, 2, 3} and B = {a, b}. The Cartesian product A × B = {(1, a), (1, b), (2, a), (2, b), (3, a), (3, b)} results in 6 ordered pairs, demonstrating pq where p = 3 and q = 2.
Distinguish between a relation and a function using example sets. Provide the conditions under which a relation qualifies as a function.
A relation is any subset of the Cartesian product of two sets. A function is a relation where each element in the domain maps to exactly one element in the codomain. For instance, R = {(1, 2), (2, 3)} is a function, while S = {(1, 2), (1, 3)} is not a function as 1 maps to two outputs.
Given the sets A = {x: x is an even integer} and B = {1, 2, 3, 4}, define a relation R from A to B where the relation only pairs each element based on a specific condition. Analyze and state whether this relation is a function.
Let R = {(2, 1), (4, 2)}. This is a function as each even integer in A is related to a unique natural number from B. The relation pairs even numbers to their order in the set B.
Consider the function f(x) = 3x + 1. Find the domain and range assuming the function maps from real numbers to real numbers.
The domain of f is all real numbers (R). The range is also all real numbers, as for any real number y, there exists a unique x such that y = 3x + 1 (specifically x = (y - 1)/3).
Illustrate the concept of domain and range by defining a relation R = {(1,2), (2,3), (3,4)}. Determine the domain and range of this relation.
The domain of R = {1, 2, 3} and the range = {2, 3, 4}. Each first element is part of the domain, while each second element is part of the range.
Explain what is meant by the range of a function, using the function f(x) = x^2. Find the range when the domain is restricted to non-negative real numbers.
The range of f(x) = x², when the domain is restricted to non-negative real numbers, is [0, ∞) since the output is always non-negative.
Demonstrate the use of function notation by defining a function g defined by g(x) = 2x^2 - x + 3. Determine g(1) and g(-1). Calculate these values and provide a brief explanation of how function notation works.
g(1) = 2(1)² - (1) + 3 = 4; g(-1) = 2(-1)² - (-1) + 3 = 6. Function notation allows us to compute and express the output of a function for specific input values.
Given two sets A = {1, 2} and B = {a, b, c}, calculate and list the Cartesian product A × B. Identify common misconceptions students might have when calculating Cartesian products.
The Cartesian product A × B = {(1,a), (1,b), (1,c), (2,a), (2,b), (2,c)} resulting in 6 ordered pairs. A common misconception is assuming the order of pairs does not matter or mistakenly believing the count is simply the sum of set sizes.
Evaluate whether the relation R = {(1, a), (2, b), (3, a), (3, c)} is a function. Justify your answer and explain how to determine the validity of a function.
R is not a function because the element 3 in the domain relates to two different outputs (a and c). A function must map each input to one and only one output.
Define a complex relation S from A = {1, 2, 3, 4} to B = {x, y} where each number pairs to all letters. Illustrate S and explain whether it can ever be a function.
S = {(1, x), (1, y), (2, x), (2, y), (3, x), (3, y), (4, x), (4, y)}. This relation cannot be a function because each input maps to multiple outputs.
The final worksheet presents challenging long-answer questions that test your depth of understanding and exam-readiness for Relations and Functions in Class 11.
Questions
Evaluate the implications of defining a relation R from set A to set B with R = {(x, y): y is the square of x, x ∈ A}. Discuss the restrictions this places on A and provide examples of sets for which R is a function.
Consider the set of natural numbers versus negative numbers for A. For natural numbers, every x maps to one unique y; for negatives, y cannot remain real. Counterexamples include A = {-2, -1, 0, 1, 2}. Analyze the contradiction in image values.
Discuss the role of bijective functions in real-life mappings. Provide an example of a scenario where a bijective function is essential and evaluate whether it holds true.
In an id verification system, user IDs must map uniquely to individuals. A breakdown leads to confusing identities. Analyze conditions under which bijectivity ensures correctness.
Investigate the completeness of the Cartesian product A × B when elements of A do not correlate with elements of B. Provide a mathematical representation and explain its implications.
If A = {1, 2} and B = {x, y}, the Cartesian product will yield {(1, x), (1, y), (2, x), (2, y)}. The significance is that all possible pairings exist irrespective of real-world mapping.
Explore the concept of the empty set and its relation with Cartesian products. Evaluate the situation when one set is empty.
If A is empty, A × B = φ, as there are no pairs to form. Explore implications in fields like programming or data structures.
Analyze the potential function defined by f(x) = x^2 - 4. Discuss domain and range alongside any restrictions required for it to serve as a function in a practical situation.
The function is defined for all real numbers, but explore restrictions to ensure all output values are non-negative in practical applications, which might limit the domain.
Consider the relation defined by R = {(x, y) : x + y < 10}. Analyze if R can be a function and provide specific counterpoints in assessing its validity.
R is not a function as multiple y-values exist for a single x. Example analysis with points like x=3 yields y < 7. Examine the implications of non-uniqueness.
Critically assess the uniqueness of outputs in a function from A to B given multiple definitions. Use examples from everyday functions and evaluate consequences.
Example: temperature conversion yields unique output values. Failure in uniqueness might lead to confusion or incorrect applications, especially in datasets.
Discuss the differences between one-to-one and many-to-one functions using practical situations, including advantages and disadvantages.
One-to-one allows for precise data tracking, essential in areas like banking. Evaluate the pitfalls of many-to-one in contexts such as data compression.
Evaluate the domain and range impact when introducing transformations to a set function, such as vertical translations. Use specific mathematical examples to illustrate the concept.
Considering f(x) = x^2 shifted up by 3 changes the range. Discuss functionalities in data representation, where alterations affect analytics.
Formulate the relationship between functions and their inverses using both graphical and algebraic methods. Evaluate if every function guarantees an inverse.
Graphically, one-to-one functions have invertible pairs. Algebraically, not all have inverses. Example revolves around f(x) = x^2 not being invertible.
Use this Class 11 Mathematics Relations and Functions Formula Sheet for quick revision before school exams and CBSE exams. It brings together the important formulas, key concepts, and worked examples in one place so students can revise faster and download a printable PDF for offline study.
Important Formulas
P × Q = {(p, q) : p ∈ P, q ∈ Q}
P × Q represents the Cartesian product of sets P and Q, where each element of P is paired with each element of Q. This is fundamental in defining relations.
Domain(R) = {x : (x, y) ∈ R}
The domain of relation R consists of all first elements from the ordered pairs. It represents all possible inputs for the relation.
Range(R) = {y : (x, y) ∈ R}
The range of relation R consists of all second elements from the ordered pairs. This indicates all possible outputs produced by the relation.
n(A × B) = n(A) × n(B)
If set A has p elements and set B has q elements, then the Cartesian product A × B will contain pq elements. This is crucial for counting relations.
f: A → B
A function f from set A to set B signifies that each element in A corresponds to precisely one element in B. It's a specific type of relation.
f(a) = b
This indicates that for function f, the input a from the domain A yields output b in the codomain B. It emphasizes the concept of image in function theory.
R ⊆ A × B
A relation R from set A to set B is a subset of the Cartesian product A × B, describing a relationship between elements of A and B.
x ∈ A and y ∈ B
We denote that elements x belong to set A and elements y belong to set B. This foundation is crucial for understanding relations and functions.
f + g: X → R, (f + g)(x) = f(x) + g(x)
This defines the pointwise addition of two functions f and g over set X. It's used extensively in operations on functions.
f - g: X → R, (f - g)(x) = f(x) - g(x)
This defines the pointwise subtraction of the function g from function f. It follows similar principles as addition.
Worked Examples
y = mx + c
This equation represents a linear function where m is the slope and c is the y-intercept. It is foundational in algebra for graphing straight lines.
f(x) = a0 + a1x + a2x² + ... + anxⁿ
This represents a polynomial function of degree n. Each coefficient a_i corresponds to the x raised to the power of i.
f(x) = kx, k ∈ R
This defines a constant function where k is a constant multiplier. It's essential in understanding transformations of functions.
f(x) = 2x + 1
This linear function indicates that for every x, the output is double x plus one. It's a classic example used in function applications.
g(x) = x²
This quadratic function demonstrates the parabolic relationship where output is the square of the input. It's fundamental in algebra.
h(x) = 1/x, x ≠ 0
This defines a rational function. It's essential in higher algebra and calculus to work with domains exceeding standard real numbers.
R = { (x, y) : y = f(x) }
A way to represent a relation in terms of a function f. It indicates that y is determined by the input x through function f.
f(x) = |x|
The modulus function reflects all negative inputs to their positive counterparts, crucial in understanding numeric boundaries.
f/g, g(x) ≠ 0
This represents the division of two functions where g(x) is non-zero. Important in the analysis of rational functions and their limits.
f(x) = 2x - 3
This linear equation delineates the relationship between x and its corresponding outputs through a slope and intercept.
Explore More Relations and Functions Resources
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Relations and Functions Official Textbook PDF
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Relations and Functions Revision Guide
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Relations and Functions Formula Sheet
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Relations and Functions Practice Worksheet
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Relations and Functions Mastery Worksheet
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Relations and Functions Challenge Worksheet
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Relations and Functions Question Bank
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