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Relations and Functions (Class 12) · Question 26

JEE Main 2025 (Online) 4th April Evening ShiftMCQEasy📈 Topic in 45% papers+4−1
1

Let A = \-3, -2, -1, 0, 1, 2, 3\ and R be a relation on A defined by xRy if and only if 2x - y \0, 1\. Let l be the number of elements in R. Let m and n be the minimum number of elements required to be added in R to make it reflexive and symmetric relations, respectively. Then l + m + n is equal to:

  1. 17
  2. 18
  3. 15
  4. 16

Answer

(1) 17

Solution

xRy y = 2x or y = 2x - 1, with x, y A.

x = -3: y = -6, -7 (not in A)

x = -2: y = -4, -5 (not in A)

x = -1: y = -2, -3 (-1, -2), (-1, -3)

x = 0: y = 0, -1 (0, 0), (0, -1)

x = 1: y = 2, 1 (1, 2), (1, 1)

x = 2: y = 4, 3 (2, 3)

x = 3: y = 6, 5 (not in A)

l = 7

Reflexive: all 7 pairs (a, a) are needed; only (0, 0) and (1, 1) are present m = 7 - 2 = 5

Symmetric: the reverses (-2, -1), (-3, -1), (-1, 0), (2, 1), (3, 2) are all missing n = 5

l + m + n = 7 + 5 + 5 = 17

Answer: (1)

JEE Main 2025 (Online) 4th April Evening Shift

Keep practising — Relations and Functions (Class 12)

2

Let A = \-3, -2, -1, 0, 1, 2, 3\. Let R be a relation on A defined by x R y if and only if 0 x2 + 2y 4. Let l be the number of elements in R and m be the minimum number of elements required to be added in R to make it a reflexive relation. Then l + m is equal to

  1. 18
  2. 20
  3. 17
  4. 19
JEE Main 2025 (Online) 3rd April Morning Shift
3

Let f be a function such that f(x) + 3f ( 24x ) = 4x, x 0. Then f(3) + f(8) is equal to

  1. 13
  2. 11
  3. 10
  4. 12
JEE Main 2025 (Online) 3rd April Evening Shift
4

Let A = \-2, -1, 0, 1, 2, 3\. Let R be a relation on A defined by xRy if and only if y = \x, 1\. Let l be the number of elements in R. Let m and n be the minimum number of elements required to be added in R to make it reflexive and symmetric relations, respectively. Then l + m + n is equal to

  1. 11
  2. 12
  3. 14
  4. 13
JEE Main 2025 (Online) 3rd April Evening Shift
5

Let f : R R be a twice differentiable function such that ( x y)(f(2x + 2y) - f(2x - 2y)) = ( x y)(f(2x + 2y) + f(2x - 2y)), for all x, y R. If f'(0) = 12, then the value of 24f'' ( 5 3 ) is :

  1. 2
  2. 3
  3. -3
  4. -2
JEE Main 2025 (Online) 2nd April Morning Shift
6

Let A be the set of all functions f : Z Z and R be a relation on A such that R = \(f, g) : f(0) = g(1) and f(1) = g(0)\. Then R is :

  1. Symmetric and transitive but not reflexive
  2. Symmetric but neither reflexive nor transitive
  3. Transitive but neither reflexive nor symmetric
  4. Reflexive but neither symmetric nor transitive
JEE Main 2025 (Online) 2nd April Morning Shift
7

Define a relation R on the interval [0, 2 ) by x R y if and only if 2 x - 2 y = 1. Then R is :

  1. both reflexive and symmetric but not transitive
  2. both reflexive and transitive but not symmetric
  3. reflexive but neither symmetric nor transitive
  4. an equivalence relation
JEE Main 2025 (Online) 29th January Morning Shift
8

If f(x) = 2x2x + 2, x R, then k=181 f ( k82 ) is equal to

  1. 82
  2. 81 2
  3. 41
  4. 812
JEE Main 2025 (Online) 28th January Morning Shift
9

The relation R = \(x, y) : x, y Z and x + y is even\ is:

  1. reflexive and transitive but not symmetric
  2. reflexive and symmetric but not transitive
  3. an equivalence relation
  4. symmetric and transitive but not reflexive
JEE Main 2025 (Online) 28th January Morning Shift
10

Let f: R - \0\ (- , 1) be a polynomial of degree 2, satisfying f(x)f ( 1x ) = f(x) + f ( 1x ). If f(K) = -2K, then the sum of squares of all possible values of K is:

  1. 9
  2. 1
  3. 6
  4. 7
JEE Main 2025 (Online) 28th January Evening Shift
11

Let f : [0, 3] A be defined by f(x) = 2x3 - 15x2 + 36x + 7 and g : [0, ) B be defined by g(x) = x2025x2025 + 1. If both the functions are onto and S = \x Z; x A or x B\, then n(S) is equal to :

  1. 29
  2. 31
  3. 30
  4. 36
JEE Main 2025 (Online) 28th January Evening Shift

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