

NCERT Solutions Class 12 Maths Chapter 1 PDF Download Link
NCERT Solutions for Class 12 Physics
Solve The Following Questions NCERT Solutions for Class 12 Maths Chapter 1 Excercise 1.1 (Relations and Functions):
Question 1. Determine whether each of the following relations are reflexive, symmetric and transitive: (i)Relation R in the set A = {1, 2, 3…13, 14} defined as R = {(x, y): 3x − y = 0} (ii) Relation R in the set N of natural numbers defined as R = {(x, y): y = x + 5 and x < 4} (iii) Relation R in the set A = {1, 2, 3, 4, 5, 6} as R = {(x, y): y is divisible by x} (iv) Relation R in the set Z of all integers defined as R = {(x, y): x − y is as integer} (v) Relation R in the set A of human beings in a town at a particular time given by (a) R = {(x, y): x and y work at the same place} (b) R = {(x, y): x and y live in the same locality} (c) R = {(x, y): x is exactly 7 cm taller than y} (d) R = {(x, y): x is wife of y} (e) R = {(x, y): x is father of y}NCERT Solutions for Class 12 Maths Chapter 1 Exercise 1.2
Question 2. Show that the relation R in the set R of real numbers, defined as R = {(a, b): a ≤ b 2 } is neither reflexive nor symmetric nor transitive. Solution : R = {(a, b): a ≤ b 2 } , Relation R is defined as the set of real numbers. It can be observed that
∴R is not reflexive. Now, (1, 4) ∈ R as 1 < 4 2 But, 4 is not less than 1 2 . ∴(4, 1) ∉ R ∴R is not symmetric. Now, (3, 2), (2, 1.5) ∈ R (as 3 < 2 2 = 4 and 2 < (1.5) 2 = 2.25) But, 3 > (1.5) 2 = 2.25 ∴(3, 1.5) ∉ R ∴ R is not transitive. Hence, R is neither reflexive, nor symmetric, nor transitive.
NCERT Solutions for Class 12 Maths Chapter 1 Exercise 1.3
Question 3. Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b): b = a + 1} is reflexive, symmetric or transitive. Solution : Let A = {1, 2, 3, 4, 5, 6}. A relation R is defined on set A as: R = {(a, b): b = a + 1} ∴R = {(1, 2), (2, 3), (3, 4), (4, 5), (5, 6)} We can find (a, a) ∉ R, where a ∈ A. For instance, (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6) ∉ R ∴R is not reflexive. It can be observed that (1, 2) ∈ R, but (2, 1) ∉ R. ∴R is not symmetric. Now, (1, 2), (2, 3) ∈ R But, (1, 3) ∉ R ∴R is not transitive Hence, R is neither reflexive, nor symmetric, nor transitive.NCERT Solutions for Class 12 Maths Chapter 1 Exercise 1.4
Question 4. Show that the relation R in R defined as R = {(a, b): a ≤ b}, is reflexive and transitive but not symmetric. Solution : R = {(a, b); a ≤ b} Clearly (a, a) ∈ R as a = a. ∴R is reflexive. Now, (2, 4) ∈ R (as 2 < 4) But, (4, 2) ∉ R as 4 is greater than 2. ∴ R is not symmetric. Now, let (a, b), (b, c) ∈ R. Then, a ≤ b and b ≤ c ⇒ a ≤ c ⇒ (a, c) ∈ R ∴R is transitive. Hence,R is reflexive and transitive but not symmetric.NCERT Solutions for Class 12 Maths Chapter 1 Miscellaneous Exercise
Question 5. Check whether the relation R in R defined as R = {(a, b): a ≤ b 3 } is reflexive, symmetric or transitive. Solution :
Question 6. Show that the relation R in the set {1, 2, 3} given by R = {(1, 2), (2, 1)} is symmetric but neither reflexive nor transitive. 