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Sets, Relations and Functions appeared 65 times across 3 years — 7.5% of Mathematics. This question is from Composite Functions.

Year 2026 2025 2024 Total
Questions 19 31 15 65

If f(x)= cases2+2x,& -1≤ x lt 0 1-(x)/(3),& 0≤ x≤ 3 cases; g(x)= cases-x,& -3≤ x≤ 0 x,& 0 lt x≤ 1 cases , then range of (fog(x)) is

Solution & Explanation

Related Formula
f(g(x)) = f(y) where y = g(x)

The domain restrictions of f(y) must be cross-checked against the range evaluated for g(x).

Core Logic

First, analyze the range of the inner function g(x): g(x) = -x for -3 ≤ x ≤ 0. The range here is [0, 3]. g(x) = x for 0 lt x ≤ 1. The range here is (0, 1]. Therefore, the complete range of g(x) across its entire domain [-3, 1] is [0, 3]. Note that g(x) ≥ 0 for all valid x.

Composite Functions
Composite Functions

Now, plug g(x) into f(x):

f(g(x)) = cases2+2g(x),& -1 ≤ g(x) lt 0 (1) 1-(g(x))/(3),& 0 ≤ g(x) ≤ 3 (2) cases

Composite Functions
Composite Functions

Step 1: Evaluate the Branches

Check branch (1): -1 ≤ g(x) lt 0. Since we already established the range of g(x) is entirely non-negative (g(x) ≥ 0), this branch condition is never satisfied. No values of x map here (x in φ).

Check branch (2): 0 ≤ g(x) ≤ 3. This perfectly aligns with the entire range of g(x). Hence, this branch is active for all x in [-3, 1]. We evaluate f(g(x)) = 1 - (g(x))/(3). Since g(x) spans all values continuously from 0 to 3: When g(x) = 0 ⇒ f(g(x)) = 1 - 0 = 1. When g(x) = 3 ⇒ f(g(x)) = 1 - 1 = 0.

Since g(x) is continuous and covers [0, 3], 1 - (g(x))/(3) covers [0, 1] continuously.

Step 2: Final Conclusion

The range of f(g(x)) is purely evaluated from branch (2), leading to [0, 1].

Pattern Recognition

When finding the range of f(g(x)), evaluate the global range of g(x) first. Use that resulting interval as the "domain" input for f(x) to trace the final output bounds, eliminating unneeded piecewise branches.

Chapter Mix

Class 11 Mathematics: Sets, Relations and Functions

Reference Study Guides

More Sets, Relations and Functions Previous-Year Questions — Page 3

Q5 jee_main_2026_23_january_evening Onto Functions
Consider two sets A = xin Z:|(|x - 3| - 3)|≤ 1 and B = xin R - 1,2 :((x - 2)(x - 4))/(x - 1) ₑ(|x - 2|) = 0. Then the number of onto functions f: A → B is equal to:
  • A. 62
  • B. 79
  • C. 32
  • D. 81

Solution

Related Formula

Number of onto functions from a set A (size m) to a set B (size n) when n=2 is given by: 2^m - 2

Core Logic

Find elements of set A:

||x - 3| - 3| ≤ 1 -1 ≤ |x - 3| - 3 ≤ 1 2 ≤ |x - 3| ≤ 4

This yields two cases: Case 1: 2 ≤ x - 3 ≤ 4 5 ≤ x ≤ 7 Case 2: -4 ≤ x - 3 ≤ -2 -1 ≤ x ≤ 1 Since x in Z, the elements are A = -1, 0, 1, 5, 6, 7. Total elements n(A) = 6.

Step 1: Find Elements of B

For set B, solve the equation:

((x - 2)(x - 4))/(x - 1) ₑ(|x - 2|) = 0

This product is 0 if any of the following is true (and defined):

  • x - 4 = 0 x = 4
  • ₑ(|x - 2|) = 0 |x - 2| = 1 x = 3 or x = 1
  • However, B is defined for x in R - 1, 2. Thus x=1 is rejected. So, B = 3, 4. Total elements n(B) = 2.

Step 2: Calculate Onto Functions

We need the number of onto functions from a set of 6 elements to a set of 2 elements:

Number of onto functions = 2⁶ - 2 = 64 - 2 = 62
Pattern Recognition

When asked for onto functions to a 2-element set, calculate 2^m total mappings and subtract the 2 trivial cases where all elements map to exactly one of the targets.

Chapter Mix

Class 11 Maths: Sets, Relations and Functions Class 11 Maths: Linear Inequalities

Q16 jee_main_2026_23_january_evening Equivalence Relation
Let A = 0, 1, 2, 9. Let R be a relation on A defined by (x, y) in R if and only if |x-y| is a multiple of 3. Given below are two statements: Statement I: n(R) = 36 Statement II: R is an equivalence relation. In the light of the above statements, choose the correct answer from the options given below
  • A. Both Statement I and Statement II are correct
  • B. Statement I is incorrect but Statement II is correct
  • C. Statement I is correct but Statement II is incorrect
  • D. Both Statement I and Statement II are incorrect

Solution

Related Formula

A relation is an equivalence relation if it is reflexive, symmetric, and transitive.

Core Logic

First, partition set A into equivalence classes modulo 3: Numbers of form 3K: 0, 3, 6, 9 4 elements Numbers of form 3K+1: 1, 4, 7 3 elements Numbers of form 3K+2: 2, 5, 8 3 elements

Any pair (x, y) inside the same group will have a difference |x - y| that is a multiple of 3. The total number of elements in the relation R is the sum of pairs possible from each group:

n(R) = 4 × 4 + 3 × 3 + 3 × 3 n(R) = 16 + 9 + 9 = 34

Statement I claims n(R) = 36, so it is false.

Step 1: Check Statement II

Reflexive: |x-x| = 0, which is a multiple of 3. (True) Symmetric: If |x-y| is a multiple of 3, then |y-x| is also a multiple of 3. (True) Transitive: If (x-y) = 3λ and (y-z) = 3μ, then (x-z) = (x-y) + (y-z) = 3(λ + μ), which is a multiple of 3. (True) Thus, R is an equivalence relation. Statement II is true.

Pattern Recognition

Relations defined by divisibility of differences inherently form congruence classes. Size of relation = sum of squares of equivalence class sizes.

Chapter Mix

Class 11 Maths: Sets, Relations and Functions

Q6 jee_main_2026_24_january_morning Domain of Logarithmic Functions
If the domain of the function f(x) = (10x²-17x+7) (18x²-11x+1) is (-∞, a) (b, c) (d, ∞) - e, then 90(a+b+c+d+e) equals:
  • A. 170
  • B. 177
  • C. 307
  • D. 316

Solution

Related Formula
y = B(A) ⇒ A > 0, B > 0, B ≠ 1
Core Logic

For the domain, three conditions must be satisfied:

  • Argument > 0: 18x² - 11x + 1 > 0
  • Base > 0: 10x² - 17x + 7 > 0
  • Base ≠ 1: 10x² - 17x + 7 ≠ 1
Step 1: Argument Condition
18x² - 11x + 1 > 0 (2x - 1)(9x - 1) > 0

x < (1)/(9) or x > (1)/(2)

Step 2: Base Positivity
10x² - 17x + 7 > 0 (x - 1)(10x - 7) > 0

x < (7)/(10) or x > 1

Step 3: Base Not Equal to 1
10x² - 17x + 7 ≠ 1 10x² - 17x + 6 ≠ 0 (5x - 6)(2x - 1) ≠ 0 ⇒ x ≠ (6)/(5), x ≠ (1)/(2)
Step 4: Intersection and Value Evaluation

Taking the intersection of all conditions: x in (-∞, (1)/(9)) ((1)/(2), (7)/(10)) (1, ∞) - (6)/(5) Comparing with (-∞, a) (b, c) (d, ∞) - e: a = (1)/(9), b = (1)/(2), c = (7)/(10), d = 1, e = (6)/(5)

90(a+b+c+d+e) = 90((1)/(9) + (1)/(2) + (7)/(10) + 1 + (6)/(5)) = 10 + 45 + 63 + 90 + 108 = 316
Pattern Recognition

A standard combined inequality problem. Always factorize quadratics early and map the boundaries on a number line to prevent overlapping interval errors.

Chapter Mix

Class 11 Maths: Relations and Functions Class 11 Maths: Linear Inequalities

Q12 jee_main_2026_24_january_morning Equivalence Relations on Sets
Let R be a relation defined on the set 1, 2, 3, 4 × 1, 2, 3, 4 by R = ((a, b), (c, d)) : 2a + 3b = 3c + 4d. Then the number of elements in R is
  • A. 6
  • B. 18
  • C. 12
  • D. 15

Solution

Related Formula

Count combinations (a, b) and (c, d) from the set S = 1, 2, 3, 4 fulfilling 2a + 3b = 3c + 4d.

Core Logic

Evaluate possible values for LHS = 2a + 3b where a,b in 1, 2, 3, 4. Min value = 5, Max value = 20. Evaluate RHS = 3c + 4d where c,d in 1, 2, 3, 4. Find exact matches.

Step 1: Mapping Outputs

(a,b) pairs mapped to 2a+3b(c,d) pairs mapped to 3c+4d
(1,1) → 5, (1,2) → 8, (1,3) → 11, (1,4) → 14(1,1) → 7, (1,2) → 11, (1,3) → 15, (1,4) → 19
(2,1) → 7, (2,2) → 10, (2,3) → 13, (2,4) → 16(2,1) → 10, (2,2) → 14, (2,3) → 18, (2,4) → 22
(3,1) → 9, (3,2) → 12, (3,3) → 15, (3,4) → 18(3,1) → 13, (3,2) → 17, (3,3) → 21, (3,4) → 25
(4,1) → 11, (4,2) → 14, (4,3) → 17, (4,4) → 20(4,1) → 16, (4,2) → 20, (4,3) → 24, (4,4) → 28

Step 2: Counting Intersections

Matches found: Value 7: (2,1) matches (1,1) → 1 pair Value 10: (2,2) matches (2,1) → 1 pair Value 11: (1,3), (4,1) match (1,2) → 2 pairs Value 13: (2,3) matches (3,1) → 1 pair Value 14: (1,4), (4,2) match (2,2) → 2 pairs Value 15: (3,3) matches (1,3) → 1 pair Value 16: (2,4) matches (4,1) → 1 pair Value 17: (4,3) matches (3,2) → 1 pair Value 18: (3,4) matches (2,3) → 1 pair Value 20: (4,4) matches (4,2) → 1 pair

Total matches = 1+1+2+1+2+1+1+1+1+1 = 12.

Pattern Recognition

For tiny finite sets, brute forcing the 4 × 4 = 16 mappings of LHS and RHS separately and tallying equal values is the quickest algorithm to avoid counting logic errors.

Chapter Mix

Class 11 Maths: Relations and Functions

Q13 jee_main_2026_24_january_evening Domain of Inverse Trigonometric Functions
If the domain of the function f(x) = ⁻¹ ( 1x² - 2x - 2 ), is (-∞, α] [β, γ] [δ, ∞), then α + β + γ + δ is equal to
  • A. 2
  • B. 4
  • C. 3
  • D. 5

Solution

Related Formula
For y = ⁻¹(g(x)), the domain is given by -1 ≤ g(x) ≤ 1
Core Logic

For f(x) = ⁻¹((1)/(x² - 2x - 2)), the inner argument must lie in [-1, 1].

-1 ≤ (1)/(x² - 2x - 2) ≤ 1
Step 1: Solving Right Inequality
(1)/(x² - 2x - 2) ≤ 1 (1)/(x² - 2x - 2) - 1 ≤ 0 (1 - x² + 2x + 2)/(x² - 2x - 2) ≤ 0 (x² - 2x - 3)/(x² - 2x - 2) ≥ 0

Factorize numerator and denominator: Numerator roots: x² - 2x - 3 = (x - 3)(x + 1) Denominator roots: x² - 2x - 2 = 0 x = 2 ± √(4 + 8)2 = 1 ± √(3)

(x - 3)(x + 1)(x - (1 - √(3)))(x - (1 + √(3))) ≥ 0

Using the wavy curve method, the intervals are: x in (-∞, -1] (1 - √(3), 1 + √(3)) [3, ∞) --- (1)

Step 2: Solving Left Inequality
(1)/(x² - 2x - 2) ≥ -1 (1)/(x² - 2x - 2) + 1 ≥ 0 (x² - 2x - 1)/(x² - 2x - 2) ≥ 0

Factorize numerator roots: x² - 2x - 1 = 0 x = 2 ± √(4 + 4)2 = 1 ± √(2)

(x - (1 - √(2)))(x - (1 + √(2)))(x - (1 - √(3)))(x - (1 + √(3))) ≥ 0

Using the wavy curve method, the intervals are: x in (-∞, 1 - √(3)) [1 - √(2), 1 + √(2)] (1 + √(3), ∞) --- (2)

Step 3: Intersection of Intervals

Take the intersection of (1) and (2). Note that: 1 - √(3) ≈ 1 - 1.732 = -0.732 1 - √(2) ≈ 1 - 1.414 = -0.414 1 + √(2) ≈ 1 + 1.414 = 2.414 1 + √(3) ≈ 1 + 1.732 = 2.732

Intersection gives: x in (-∞, -1] [1 - √(2), 1 + √(2)] [3, ∞)

Comparing this with (-∞, α] [β, γ] [δ, ∞): α = -1 β = 1 - √(2) γ = 1 + √(2) δ = 3

α + β + γ + δ = -1 + (1 - √(2)) + (1 + √(2)) + 3 = 4
Pattern Recognition

When dealing with rational polynomial inequalities for ⁻¹(g(x)), always break into -1 ≤ g(x) and g(x) ≤ 1, and do not cross-multiply terms across the inequality if the sign of the denominator is undetermined.

Chapter Mix

Class 12 Maths: Inverse Trigonometric Functions Class 11 Maths: Functions

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