Table of Contents
Exercise Ex. 1.1
Solution 1
Hence: this collection is a set. (vii) The collection of all even integers is a well-defined collection because one can definitely identify an even integer that belongs to this collection. Hence: this collection is a set.
(viii) The collection of questions in this chapter is a well-defined collection because one can definitely identify a question that belongs to this chapter.
Hence: this collection is a set.
(ix) The collection ofmost dangerous animals of the world is not a well-defined collection because the criteria for determining the dangerousness of an animal can vary from person to person.
Hence: this collection is not a set.Solution 2
Solution 3
(i) A = { x : x is an integer and -3 ≤ x < 7}.
The elements of this set are -3, -2, -1, 0, 1, 2, 3, 4, 5 and 6 only.
Therefore, the given set can written in roster form as
A = {-3, -2, -1, 0, 1, 2, 3, 4, 5, 6}
(ii) B = { x : x is a natural number less than 6}
The elements of this set are 1, 2, 3, 4 and 5 only.
Therefore, the given set can written in roster form as
B = {1, 2, 3, 4, 5}
(iii) C = { x : x is a two-digit number such that the sum of its digits is 8}
The elements of this set are 17, 26, 35, 44, 53, 62, 71 and 80 only.
Therefore, the given set can written in roster form as
C = {17, 26, 35, 44, 53, 62, 71, 80}
(iv) D = { x : x is a prime number which is divisor of 60}.
| 2 | 60 |
| 2 | 30 |
| 3 | 15 |
| 5 |
∴ 60 = 2 × 2 × 3 × 5
The elements of this set are 2, 3 and 5 only.
Therefore, this set can written in roster form as D = {2, 3, 5}.
(v) E = The set of all letters in the word TRIGONOMETRY.
There are 12 letters in the word TRIGONOMETRY, out of which letters T, R, and O are repeated.
Therefore, this set can written in roster form as
E = {T, R, I, G, O, N, M, E, Y}
(vi) F = The set of all letters in the word BETTER.
There are 6 letters in the word BETTER, out of which letters E and T are repeated.
Therefore, this set can written in roster form as
F = {B, E, T, R}Solution 4
Solution 5
Solution 6
Exercise Ex. 1.2
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Exercise Ex. 1.3
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
Solution 7
Solution 8
Solution 9
Exercise Ex. 1.4
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
Solution 7
Solution 8
Solution 9
Solution 10
Solution 11
Solution 12
Exercise Ex. 1.5
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
Solution 7
Exercise Ex. 1.6
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
Solution 7
Solution 8
Exercise Misc. Ex.
Solution 1
Solution 2
Solution 3
Solution 4
Solution 5
Solution 6
Solution 7
Solution 8
Solution 9
Solution 10
Solution 11
Solution 12
Solution 13
Solution 14
Solution 15
Solution 16
