# NCERT Solutions for Class 11th Maths Exercise 1.5 Set

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views CBSE NCERT Solutions For Class 11th Maths Chapter 1 : Set. NCERT Solutins For Class 11 Mathematics. Exercise 1.1, Exercise 1.2, Exercise 1.3, Exercise 1.4, Exercise 1.5, Exercise 1.6,  (Miscellaneous Excercise) many more solutions

Exercise 1.5

Question 1:

Let U ={1, 2, 3; 4, 5, 6, 7, 8, 9}, A = {1, 2, 3, 4}, B = {2, 4, 6, 8} and C = {3, 4, 5, 6}. Find

1. 2.  1. 2. 3. 4. U ={1, 2, 3, 4, 5, 6, 7, 8, 9}

A = {1, 2, 3, 4}

B = {2, 4, 6, 8}

C = {3, 4, 5, 6}

(i) (ii) (iii)  (iv)  (v) (vi)  Question 2:

If U = {a, b, c, d, e, f, g, h}, find the complements of the following sets:

1. A = {a, b, c}
2. B = {d, e, f, g} 1. C = {a, c, e, g}
2. D = {f, g, h, a} Answer

U = {a, b, c, d, e, f, g, h}

1. A = {a, b, c}
2. B = {d, e, f, g}
3. C = {a, c, e, g}
4. D = {f, g, h, a}    Question 3:

Taking the set of natural numbers as the universal set, write down the complements of the following sets:

1. {x: x is an even natural number}
2. {x: x is an odd natural number}
3. {x: x is a positive multiple of 3}
4. {x: x is a prime number}
5. {x: x is a natural number divisible by 3 and 5}
6. {x: x is a perfect square}
7. {x: x is perfect cube}
8. {x: x + 5 = 8}
9. {x: 2x + 5 = 9}
10. {x: x ≥ 7}
11. {x: x ∈ N and 2x + 1 > 10}

U = N: Set of natural numbers

(i) {x: x is an even natural number}´ = {x: x is an odd natural number} 1. {x: x is an odd natural number}´ = {x: x is an even natural number}
2. {x: x is a positive multiple of 3}´ = {x: x ∈ N and x is not a multiple of 3}
3. {x: x is a prime number}´ ={x: x is a positive composite number and x = 1}
4. {x: x is a natural number divisible by 3 and 5}´ = {x: x is a natural number that is not divisible by 3 or 5}
5. {x: x is a perfect square}´ = {x: x ∈ N and x is not a perfect square}
6. {x: x is a perfect cube}´ = {x: x ∈ N and x is not a perfect cube}
7. {x: x + 5 = 8}´ = {x: x ∈ N and x ≠ 3}
8. {x: 2x + 5 = 9}´ = {x: x ∈ N and x ≠ 2}
9. {x: x ≥ 7}´ = {x: x ∈ N and x < 7}
10. {x: x ∈ N and 2x + 1 > 10}´ = {x: x ∈ N and x ≤ 9/2}

Question 4:

If U = {1, 2, 3, 4, 5,6,7,8, 9}, A = {2, 4, 6, 8} and B = {2, 3, 5, 7}. Verify that

(i) (ii) U = {1, 2, 3, 4, 5, 6, 7, 8, 9}

A = {2, 4, 6, 8}, B = {2, 3, 5, 7}

(i) (ii) Question 5:

Draw appropriate Venn diagram for each of the following: 1. 2. 3. 4. (i)  (ii)  (iii)  (iv)   Question 6:

Let U be the set of all triangles in a plane. If A is the set of all triangles with at least one angle different from 60°, what is ? is the set of all equilateral triangles.

Question 7:

Fill in the blanks to make each of the following a true statement:

(i) (ii) Φ′ A = …

(iii) (iv) (i) (ii) Φ′ A = U A = A

∴ Φ′ ∩ A = A

1. A ∩ A′ = Φ
2. U′ ∩ A = Φ ∩ A = Φ

∴ U′ ∩ A = Φ