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By Shailendra Singh
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Updated on 23 Jul 2026, 11:42 IST
NCERT Solutions for Class 11 Maths Chapter 2 Relations and Functions 2026-27 provide clear, step-by-step answers to all questions given in the latest NCERT Mathematics textbook. These solutions help students understand the basic ideas of relations and functions in simple words and prepare well for school exams, assignments, and future competitive exams.
In this chapter, students learn how two sets can be connected through ordered pairs. The chapter begins with the Cartesian product of sets and explains how ordered pairs are formed. It then introduces relations, their meaning, and their representation. Students also study functions, domain, codomain, and range. Easy examples make it simpler to understand how every function is a relation, but every relation is not always a function.
The NCERT Solutions for Class 11 Maths Chapter 2 Relations and Functions explain each exercise question in a logical and student-friendly way. Important definitions, formulas, symbols, and methods are presented clearly so that learners can solve problems without confusion. The solutions are useful for quick revision because they follow the same order and method as the NCERT textbook.
By using these chapter solutions, students can improve their understanding of concepts, check their answers, correct mistakes, and learn the right steps for solving questions. They can also build a strong base for later topics such as inverse trigonometric functions, calculus, and algebra.
Download NCERT Solutions for Class 11 Maths Chapter 2 Relations and Functions PDF to study the chapter easily anytime and anywhere. The PDF includes clear, step-by-step solutions to NCERT questions on Cartesian products, relations, functions, domain, codomain, and range. Students can use the Class 11 Maths Chapter 2 PDF for quick revision, homework help, and self-study during the 2026-27 academic session. It is a useful study resource for learners searching for accurate and easy NCERT Solutions for Class 11 Maths Chapter 2 Relations and Functions.
Question 1: If ((x/3) + 1, y - (2/3)) = (5/3, 1/3), find the values of x and y.
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Solution:
Two ordered pairs are equal only when their corresponding components are equal.
Therefore:
(x/3) + 1 = 5/3

and
y - (2/3) = 1/3

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Finding x:
(x/3) + 1 = 5/3
x/3 = (5/3) - 1
x/3 = (5/3) - (3/3)

x/3 = 2/3
x = 2
Finding y:
y - (2/3) = 1/3
y = (1/3) + (2/3)
y = 3/3
y = 1
Final answer: x = 2 and y = 1.
Question 2: A set A has 3 elements and B = {3, 4, 5}. Find the number of elements in A × B.
Solution:
The number of elements in a Cartesian product is found by multiplying the number of elements in the two sets.
n(A × B) = n(A) × n(B)
Here, n(A) = 3 and n(B) = 3.
Therefore:
n(A × B) = 3 × 3 = 9
Final answer: A × B has 9 elements.
Question 3: If G = {7, 8} and H = {5, 4, 2}, find G × H and H × G.
Solution:
In G × H, the first component of every ordered pair comes from G and the second component comes from H.
G × H:
G × H = {(7, 5), (7, 4), (7, 2), (8, 5), (8, 4), (8, 2)}
In H × G, the first component comes from H and the second component comes from G.
H × G:
H × G = {(5, 7), (5, 8), (4, 7), (4, 8), (2, 7), (2, 8)}
Question 4: State whether each statement is true or false. Correct the statement when it is false.
(i): If P = {m, n} and Q = {n, m}, then P × Q = {(m, n), (n, m)}.
Solution:
The statement is false.
Each element of P must be paired with every element of Q.
| Element from P | Pairs formed with elements of Q |
| m | (m, n), (m, m) |
| n | (n, n), (n, m) |
Correct statement:
P × Q = {(m, n), (m, m), (n, n), (n, m)}
(ii): If A and B are non-empty sets, then A × B is a non-empty set of ordered pairs (x, y), where x belongs to A and y belongs to B.
Solution:
The statement is true. Since both sets contain at least one element, at least one ordered pair can be formed.
(iii): If A = {1, 2} and B = {3, 4}, then A × (B ∩ ∅) = ∅.
Solution:
The statement is true.
The intersection of any set with the empty set is empty.
B ∩ ∅ = ∅
Therefore:
A × (B ∩ ∅) = A × ∅ = ∅
Question 5: If A = {-1, 1}, find A × A × A.
Solution:
Every ordered triple in A × A × A has the form (p, q, r), where p, q and r are selected from A.
Since A has 2 elements, the number of ordered triples is:
2 × 2 × 2 = 8
Therefore:
A × A × A = {
(-1, -1, -1), (-1, -1, 1), (-1, 1, -1), (-1, 1, 1),
(1, -1, -1), (1, -1, 1), (1, 1, -1), (1, 1, 1)
}
Question 6: If A × B = {(a, x), (a, y), (b, x), (b, y)}, find A and B.
Solution:
The first components of the ordered pairs belong to A, while the second components belong to B.
| Position | Distinct elements | Set |
| First component | a, b | A = {a, b} |
| Second component | x, y | B = {x, y} |
Final answer: A = {a, b} and B = {x, y}.
Question 7: Let A = {1, 2}, B = {1, 2, 3, 4}, C = {5, 6} and D = {5, 6, 7, 8}. Verify the following statements.
(i): A × (B ∩ C) = (A × B) ∩ (A × C)
Solution:
The sets B and C have no common element.
Therefore:
B ∩ C = ∅
A × (B ∩ C) = A × ∅ = ∅
Now calculate the sets on the right-hand side.
A × B = {(1, 1), (1, 2), (1, 3), (1, 4), (2, 1), (2, 2), (2, 3), (2, 4)}
A × C = {(1, 5), (1, 6), (2, 5), (2, 6)}
These Cartesian products have no common ordered pair. Hence:
(A × B) ∩ (A × C) = ∅
Thus, both sides are equal:
A × (B ∩ C) = (A × B) ∩ (A × C) = ∅
(ii) Verify that A × C is a subset of B × D.
Solution:
First calculate A × C:
A × C = {(1, 5), (1, 6), (2, 5), (2, 6)}
Now calculate B × D:
B × D = {
(1, 5), (1, 6), (1, 7), (1, 8),
(2, 5), (2, 6), (2, 7), (2, 8),
(3, 5), (3, 6), (3, 7), (3, 8),
(4, 5), (4, 6), (4, 7), (4, 8)
}
Every ordered pair of A × C is also present in B × D.
Therefore, A × C is a subset of B × D.
Question 8 Let A = {1, 2} and B = {3, 4}. Write A × B. How many subsets does A × B have? List them.
Solution:
A × B = {(1, 3), (1, 4), (2, 3), (2, 4)}
Let:
p = (1, 3), q = (1, 4), r = (2, 3) and s = (2, 4).
The set A × B has 4 elements. A set with n elements has 2n subsets.
Number of subsets = 24 = 16
| Number of elements | Subsets |
| 0 | ∅ |
| 1 | {p}, {q}, {r}, {s} |
| 2 | {p, q}, {p, r}, {p, s}, {q, r}, {q, s}, {r, s} |
| 3 | {p, q, r}, {p, q, s}, {p, r, s}, {q, r, s} |
| 4 | {p, q, r, s} |
Replacing p, q, r and s by the ordered pairs, the 16 subsets are:
∅,
{(1, 3)}, {(1, 4)}, {(2, 3)}, {(2, 4)},
{(1, 3), (1, 4)}, {(1, 3), (2, 3)}, {(1, 3), (2, 4)},
{(1, 4), (2, 3)}, {(1, 4), (2, 4)}, {(2, 3), (2, 4)},
{(1, 3), (1, 4), (2, 3)},
{(1, 3), (1, 4), (2, 4)},
{(1, 3), (2, 3), (2, 4)},
{(1, 4), (2, 3), (2, 4)},
{(1, 3), (1, 4), (2, 3), (2, 4)}.
Question 9: Let A and B be sets such that n(A) = 3 and n(B) = 2. If (x, 1), (y, 2) and (z, 1) belong to A × B, find A and B, where x, y and z are distinct.
Solution:
The first components x, y and z belong to A. Since they are distinct and A has exactly 3 elements:
A = {x, y, z}
The second components 1 and 2 belong to B. Since B has exactly 2 elements:
B = {1, 2}
Final answer: A = {x, y, z} and B = {1, 2}.
Question 10: The Cartesian product A × A contains 9 elements, including (-1, 0) and (0, 1). Find A and the remaining elements of A × A.
Solution:
For a finite set A:
n(A × A) = n(A) × n(A) = [n(A)]2
Given:
[n(A)]2 = 9
Therefore, n(A) = 3.
Since (-1, 0) belongs to A × A, both -1 and 0 belong to A.
Since (0, 1) belongs to A × A, both 0 and 1 belong to A.
Thus, A has the three elements -1, 0 and 1:
A = {-1, 0, 1}
Therefore:
A × A = {
(-1, -1), (-1, 0), (-1, 1),
(0, -1), (0, 0), (0, 1),
(1, -1), (1, 0), (1, 1)
}
The two given pairs are (-1, 0) and (0, 1). Hence, the remaining elements are:
{(-1, -1), (-1, 1), (0, -1), (0, 0), (1, -1), (1, 0), (1, 1)}
Question 1: Let A = {1, 2, 3, ..., 14}. A relation R from A to A is defined by:
R = {(x, y): 3x - y = 0, where x and y belong to A}
Write the domain, codomain and range of R.
Solution:
The condition is:
3x - y = 0
Therefore, y = 3x.
| x | y = 3x | Is y in A? |
| 1 | 3 | Yes |
| 2 | 6 | Yes |
| 3 | 9 | Yes |
| 4 | 12 | Yes |
| 5 | 15 | No |
For x ≥ 5, the value of 3x is greater than 14 and does not belong to A.
Therefore:
R = {(1, 3), (2, 6), (3, 9), (4, 12)}
Domain: {1, 2, 3, 4}
Codomain: A = {1, 2, 3, ..., 14}
Range: {3, 6, 9, 12}
Question 2: A relation R on the set N of natural numbers is defined by:
R = {(x, y): y = x + 5, where x is a natural number less than 4}
Write R in roster form and find its domain and range.
Solution:
The natural numbers less than 4 are 1, 2 and 3.
| x | y = x + 5 | Ordered pair |
| 1 | 6 | (1, 6) |
| 2 | 7 | (2, 7) |
| 3 | 8 | (3, 8) |
Roster form: R = {(1, 6), (2, 7), (3, 8)}
Domain: {1, 2, 3}
Range: {6, 7, 8}
Question 3: Let A = {1, 2, 3, 5} and B = {4, 6, 9}. Define a relation R from A to B by:
R = {(x, y): the difference between x and y is odd}
Write R in roster form.
Solution:
The difference of two integers is odd when one integer is odd and the other is even.
In A, the odd elements are 1, 3 and 5, while 2 is even.
In B, 4 and 6 are even, while 9 is odd.
| Element from A | Elements from B giving an odd difference | Ordered pairs |
| 1 | 4, 6 | (1, 4), (1, 6) |
| 2 | 9 | (2, 9) |
| 3 | 4, 6 | (3, 4), (3, 6) |
| 5 | 4, 6 | (5, 4), (5, 6) |
Final answer:
R = {(1, 4), (1, 6), (2, 9), (3, 4), (3, 6), (5, 4), (5, 6)}
Question 4: A relation between P = {5, 6, 7} and Q = {3, 4, 5} pairs each element x of P with x - 2 in Q.
(i) Write the relation in set-builder form.
Solution:
For every related pair, the second component is 2 less than the first component.
Therefore:
R = {(x, y): y = x - 2, x belongs to P and y belongs to Q}
(ii) Write the relation in roster form. Also find its domain and range.
Solution:
| x | y = x - 2 | Ordered pair |
| 5 | 3 | (5, 3) |
| 6 | 4 | (6, 4) |
| 7 | 5 | (7, 5) |
Roster form: R = {(5, 3), (6, 4), (7, 5)}
Domain: {5, 6, 7}
Range: {3, 4, 5}
Question 5: Let A = {1, 2, 3, 4, 6}. A relation R on A is defined by:
R = {(a, b): b is exactly divisible by a}
(i) Write R in roster form.
Solution:
| a | Elements of A divisible by a | Ordered pairs |
| 1 | 1, 2, 3, 4, 6 | (1, 1), (1, 2), (1, 3), (1, 4), (1, 6) |
| 2 | 2, 4, 6 | (2, 2), (2, 4), (2, 6) |
| 3 | 3, 6 | (3, 3), (3, 6) |
| 4 | 4 | (4, 4) |
| 6 | 6 | (6, 6) |
Therefore:
R = {(1, 1), (1, 2), (1, 3), (1, 4), (1, 6), (2, 2), (2, 4), (2, 6), (3, 3), (3, 6), (4, 4), (6, 6)}
(ii) Find the domain of R.
Solution:
Every element of A occurs as the first component of at least one ordered pair.
Domain of R: {1, 2, 3, 4, 6}
(iii) Find the range of R.
Solution:
Every element of A occurs as the second component of at least one ordered pair.
Range of R: {1, 2, 3, 4, 6}
Question 6: Find the domain and range of:
R = {(x, x + 5): x belongs to {0, 1, 2, 3, 4, 5}}
Solution:
| x | x + 5 | Ordered pair |
| 0 | 5 | (0, 5) |
| 1 | 6 | (1, 6) |
| 2 | 7 | (2, 7) |
| 3 | 8 | (3, 8) |
| 4 | 9 | (4, 9) |
| 5 | 10 | (5, 10) |
Thus:
R = {(0, 5), (1, 6), (2, 7), (3, 8), (4, 9), (5, 10)}
Domain: {0, 1, 2, 3, 4, 5}
Range: {5, 6, 7, 8, 9, 10}
Question 7: Write the relation R = {(x, x3): x is a prime number less than 10} in roster form.
Solution:
The prime numbers less than 10 are 2, 3, 5 and 7.
| x | x3 | Ordered pair |
| 2 | 8 | (2, 8) |
| 3 | 27 | (3, 27) |
| 5 | 125 | (5, 125) |
| 7 | 343 | (7, 343) |
Final answer: R = {(2, 8), (3, 27), (5, 125), (7, 343)}
Question 8: Let A = {x, y, z} and B = {1, 2}. Find the number of relations from A to B.
Solution:
A relation from A to B is any subset of A × B.
A × B = {(x, 1), (x, 2), (y, 1), (y, 2), (z, 1), (z, 2)}
Thus, A × B contains 6 elements.
A set with 6 elements has 26 subsets.
Number of relations = 26 = 64
Final answer: There are 64 relations from A to B.
Question 9: Let R be a relation on Z defined by:
R = {(a, b): a and b are integers and a - b is an integer}
Find the domain and range of R.
Solution:
The difference of any two integers is always an integer. Therefore, every pair of integers satisfies the given condition.
This means R = Z × Z.
Domain of R: Z
Range of R: Z
Question 1: Determine which of the following relations are functions. Give a reason and find the domain and range whenever the relation is a function.
(i) {(2, 1), (5, 1), (8, 1), (11, 1), (14, 1), (17, 1)}
Solution:
The first components are 2, 5, 8, 11, 14 and 17. Each one is paired with exactly one value.
Different inputs may have the same output in a function. Here, every input has the output 1.
Therefore, the relation is a function.
Domain: {2, 5, 8, 11, 14, 17}
Range: {1}
(ii) {(2, 1), (4, 2), (6, 3), (8, 4), (10, 5), (12, 6), (14, 7)}
Solution:
Every first component occurs only once and has exactly one image.
Therefore, the relation is a function.
Domain: {2, 4, 6, 8, 10, 12, 14}
Range: {1, 2, 3, 4, 5, 6, 7}
(iii) {(1, 3), (1, 5), (2, 5)}
Solution:
The input 1 is paired with two different outputs, 3 and 5.
A function cannot assign two different images to the same input.
Therefore, this relation is not a function.
Question 2: Find the domain and range of the following real functions.
(i) f(x) = -|x|
Solution:
The absolute value |x| is defined for every real number. Therefore, the domain is R.
The function can be written as:
f(x) = -x when x ≥ 0
f(x) = x when x < 0
Since |x| is always non-negative, -|x| is always less than or equal to 0.
The maximum value is 0, obtained when x = 0. As |x| becomes larger, -|x| can become as negative as required.
Domain: R
Range: (-∞, 0]
(ii) f(x) = √(9 - x2)
Solution:
For a real square root, the expression inside the square root must be non-negative.
9 - x2 ≥ 0
x2 ≤ 9
-3 ≤ x ≤ 3
Therefore, the domain is [-3, 3].
The smallest value of f(x) is 0. It occurs when x = -3 or x = 3.
The largest value is:
f(0) = √(9 - 0) = 3
Domain: [-3, 3]
Range: [0, 3]
Question 3: A function is defined by f(x) = 2x - 5. Find the following values.
(i) Find f(0).
Solution:
Substitute x = 0:
f(0) = 2 × 0 - 5
f(0) = -5
(ii) Find f(7).
Solution:
Substitute x = 7:
f(7) = 2 × 7 - 5
f(7) = 14 - 5 = 9
(iii) Find f(-3).
Solution:
Substitute x = -3:
f(-3) = 2 × (-3) - 5
f(-3) = -6 - 5 = -11
Question 4: The function t converts a temperature in degrees Celsius into degrees Fahrenheit and is defined by:
t(C) = (9C/5) + 32
(i) Find t(0).
Solution:
t(0) = (9 × 0/5) + 32
t(0) = 32
Final answer: 0°C = 32°F.
(ii) Find t(28).
Solution:
t(28) = (9 × 28/5) + 32
t(28) = 252/5 + 32
t(28) = 50.4 + 32
t(28) = 82.4
Final answer: 28°C = 82.4°F.
(iii) Find t(-10).
Solution:
t(-10) = (9 × (-10)/5) + 32
t(-10) = -18 + 32
t(-10) = 14
Final answer: -10°C = 14°F.
(iv) Find C when t(C) = 212.
Solution:
Substitute t(C) = 212 into the conversion formula:
(9C/5) + 32 = 212
9C/5 = 212 - 32
9C/5 = 180
9C = 900
C = 900/9
C = 100
Final answer: 212°F = 100°C.
Question 5: Find the range of each function.
(i) f(x) = 2 - 3x, where x is a real number and x > 0.
Solution:
Since x > 0:
3x > 0
-3x < 0
2 - 3x < 2
Therefore, f(x) is always less than 2.
As x approaches 0 from the positive side, f(x) approaches 2, but it never becomes 2 because x cannot equal 0.
As x increases without limit, 2 - 3x decreases without limit.
Range: (-∞, 2)
(ii) f(x) = x2 + 2, where x is a real number.
Solution:
For every real number x:
x2 ≥ 0
Therefore:
x2 + 2 ≥ 2
Thus, f(x) ≥ 2.
The minimum value 2 occurs when x = 0. There is no upper limit because x2 can become as large as required.
Range: [2, ∞)
(iii) f(x) = x, where x is a real number.
Solution:
This is the identity function. Every real input is returned as the output.
Therefore, every real number occurs as a value of f.
Range: R
Question 1
The relation f is defined by:
f(x) = x2 for 0 ≤ x ≤ 3
f(x) = 3x for 3 ≤ x ≤ 10
The relation g is defined by:
g(x) = x2 for 0 ≤ x ≤ 2
g(x) = 3x for 2 ≤ x ≤ 10
Show that f is a function but g is not a function.
Solution:
For f, the two rules overlap only at x = 3.
| Rule used at x = 3 | Value |
| x2 | 32 = 9 |
| 3x | 3 × 3 = 9 |
Both rules give the same output at x = 3. Every input in the domain therefore has exactly one image. Hence, f is a function.
For g, the two rules overlap at x = 2.
| Rule used at x = 2 | Value |
| x2 | 22 = 4 |
| 3x | 3 × 2 = 6 |
The same input x = 2 has two different images, 4 and 6. Therefore, g is not a function.
Question 2
If f(x) = x2, find:
(f(1.1) - f(1))/(1.1 - 1)
Solution:
First calculate the function values:
f(1.1) = (1.1)2 = 1.21
f(1) = 12 = 1
Now substitute:
(f(1.1) - f(1))/(1.1 - 1)
= (1.21 - 1)/(0.1)
= 0.21/0.1
= 2.1
Final answer: 2.1
Question 3
Find the domain of:
f(x) = (x2 + 2x + 1)/(x2 - 8x + 12)
Solution:
A rational function is undefined when its denominator is zero.
Factor the denominator:
x2 - 8x + 12
= x2 - 6x - 2x + 12
= x(x - 6) - 2(x - 6)
= (x - 2)(x - 6)
The denominator becomes zero when:
x - 2 = 0 or x - 6 = 0
Therefore, x = 2 or x = 6.
These two values must be excluded.
Domain: R - {2, 6}
Question 4
Find the domain and range of the real function f(x) = √(x - 1).
Solution:
For the square root to be real, the expression inside it must be non-negative.
x - 1 ≥ 0
x ≥ 1
Therefore, the domain is [1, ∞).
A square root is always non-negative. The smallest value is 0, obtained when x = 1. As x increases, √(x - 1) can become as large as required.
Domain: [1, ∞)
Range: [0, ∞)
Question 5
Find the domain and range of the real function f(x) = |x - 1|.
Solution:
The absolute-value expression |x - 1| is defined for every real value of x.
Therefore, the domain is R.
An absolute value cannot be negative. Its minimum value is 0, which occurs when:
x - 1 = 0
x = 1
There is no maximum value.
Domain: R
Range: [0, ∞)
Question 6
Let f be the function from R to R defined by:
f(x) = x2/(1 + x2)
Determine the range of f.
Solution:
Since x2 ≥ 0 and 1 + x2 is always positive:
x2/(1 + x2) ≥ 0
Also:
f(x) = x2/(1 + x2)
f(x) = (1 + x2 - 1)/(1 + x2)
f(x) = 1 - 1/(1 + x2)
Because 1/(1 + x2) is always positive, f(x) is always less than 1.
At x = 0:
f(0) = 0/(1 + 0) = 0
Thus, 0 is included, but 1 is not included.
To check that every number between 0 and 1 can occur, let:
y = x2/(1 + x2)
y + yx2 = x2
y = x2(1 - y)
x2 = y/(1 - y)
For every y satisfying 0 ≤ y < 1, the quantity y/(1 - y) is non-negative, so a real value of x exists.
Range: [0, 1)
Question 7
Let f, g: R → R be defined by f(x) = x + 1 and g(x) = 2x - 3. Find f + g, f - g and f/g.
Solution:
Sum of the functions:
(f + g)(x) = f(x) + g(x)
= (x + 1) + (2x - 3)
= 3x - 2
Therefore, (f + g)(x) = 3x - 2 for all real x.
Difference of the functions:
(f - g)(x) = f(x) - g(x)
= (x + 1) - (2x - 3)
= x + 1 - 2x + 3
= 4 - x
Therefore, (f - g)(x) = 4 - x for all real x.
Quotient of the functions:
(f/g)(x) = f(x)/g(x)
= (x + 1)/(2x - 3)
The denominator must not be zero:
2x - 3 ≠ 0
2x ≠ 3
x ≠ 3/2
Therefore:
(f/g)(x) = (x + 1)/(2x - 3), where x ≠ 3/2.
Question 8
Let f = {(1, 1), (2, 3), (0, -1), (-1, -3)} be defined by f(x) = ax + b, where a and b are integers. Determine a and b.
Solution:
Since (0, -1) belongs to f:
f(0) = -1
a × 0 + b = -1
b = -1
Since (1, 1) belongs to f:
f(1) = 1
a × 1 + b = 1
a + b = 1
Substitute b = -1:
a - 1 = 1
a = 2
The rule is therefore f(x) = 2x - 1.
A quick check gives:
| x | 2x - 1 | Given image |
| 2 | 3 | 3 |
| -1 | -3 | -3 |
Final answer: a = 2 and b = -1.
Question 9
Let R be a relation from N to N defined by:
R = {(a, b): a = b2}
Decide whether each statement is true or false and justify the answer.
(i) (a, a) belongs to R for every a belonging to N.
Solution:
For (a, a) to belong to R, the condition a = a2 must hold.
This does not hold for every natural number. For example, take a = 2:
22 = 4 ≠ 2
Therefore, (2, 2) does not belong to R.
The statement is false.
(ii) If (a, b) belongs to R, then (b, a) also belongs to R.
Solution:
Take a = 9 and b = 3.
Since 9 = 32, the pair (9, 3) belongs to R.
For (3, 9) to belong to R, we would need:
3 = 92 = 81
This is not true.
Therefore, (3, 9) does not belong to R.
The statement is false.
(iii) If (a, b) belongs to R and (b, c) belongs to R, then (a, c) belongs to R.
Solution:
Consider a = 16, b = 4 and c = 2.
Since 16 = 42, (16, 4) belongs to R.
Since 4 = 22, (4, 2) belongs to R.
For (16, 2) to belong to R, we would need:
16 = 22 = 4
This is false.
Thus, (16, 2) does not belong to R.
The statement is false.
Question 10
Let A = {1, 2, 3, 4}, B = {1, 5, 9, 11, 15, 16} and:
f = {(1, 5), (2, 9), (3, 1), (4, 5), (2, 11)}
Determine whether the following statements are true.
(i) f is a relation from A to B.
Solution:
A relation from A to B is any subset of A × B.
In every ordered pair of f, the first component belongs to A and the second component belongs to B.
| Ordered pair | First component in A? | Second component in B? |
| (1, 5) | Yes | Yes |
| (2, 9) | Yes | Yes |
| (3, 1) | Yes | Yes |
| (4, 5) | Yes | Yes |
| (2, 11) | Yes | Yes |
Therefore, f is a subset of A × B.
The statement is true.
(ii) f is a function from A to B.
Solution:
For f to be a function, every element of A must have exactly one image in B.
The element 2 is paired with both 9 and 11:
(2, 9) belongs to f and (2, 11) belongs to f.
Thus, one input has two different outputs.
The statement is false. The relation f is not a function from A to B.
Question 11
Let f be the subset of Z × Z defined by:
f = {(ab, a + b): a and b belong to Z}
Is f a function from Z to Z? Justify the answer.
Solution:
A function must assign exactly one output to each input.
Take a = 2 and b = 6:
ab = 2 × 6 = 12
a + b = 2 + 6 = 8
Therefore, (12, 8) belongs to f.
Now take a = -2 and b = -6:
ab = (-2) × (-6) = 12
a + b = -2 + (-6) = -8
Therefore, (12, -8) belongs to f.
The same input 12 has two different outputs, 8 and -8.
Therefore, f is not a function from Z to Z.
Question 12
Let A = {9, 10, 11, 12, 13}. A function f: A → N is defined by f(n) = the highest prime factor of n. Find the range of f.
Solution:
| n | Prime factors | Highest prime factor | f(n) |
| 9 | 3 | 3 | 3 |
| 10 | 2, 5 | 5 | 5 |
| 11 | 11 | 11 | 11 |
| 12 | 2, 3 | 3 | 3 |
| 13 | 13 | 13 | 13 |
The outputs are 3, 5, 11, 3 and 13. Repeated values are written only once in a set.
Range of f: {3, 5, 11, 13}
To solve NCERT Class 11 Relations and Functions questions, first understand the basic terms used in the chapter. These include ordered pairs, Cartesian product, relation, function, domain, codomain, and range. Learning these definitions will make the exercises easier.
The best study guide for Class 11 Maths Chapter 2 Relations and Functions 2026-27 should include simple explanations, important definitions, solved examples, exercise-wise NCERT solutions, and practice questions.
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A relation shows a connection between the elements of two sets. A function is a special type of relation in which every input has exactly one output.
Class 11 Maths Chapter 2 covers ordered pairs, Cartesian products of sets, relations, functions, domain, codomain, range, and different types of real-valued functions.
NCERT Solutions provide clear and step-by-step answers to the textbook questions. They help students understand concepts, complete homework, correct mistakes, and prepare for school examinations.
A relation can connect one input with one or more outputs. In a function, each input must have only one output. Therefore, every function is a relation, but every relation is not a function.
The domain is the set of all first elements in the ordered pairs. The range is the set of all second elements that are connected to the elements of the domain.
Students should first learn the important definitions and formulas. They should then study solved examples, complete all NCERT exercises, practise additional questions, and revise their mistakes regularly.
Students can download the NCERT Solutions for Class 11 Maths Chapter 2 Relations and Functions PDF from a reliable educational website. The PDF can be used for self-study, homework help, exam preparation, and quick revision.