Selina Textbook Solutions: Sets | Mathematics Class 8 ICSE PDF Download

 Page 1


6. Sets 
EXERCISE 6(A) 
 
Solution: 
 
Question 1. 
Write the following sets in roster (Tabular) form : 
Page 2


6. Sets 
EXERCISE 6(A) 
 
Solution: 
 
Question 1. 
Write the following sets in roster (Tabular) form : 
 
 
Page 3


6. Sets 
EXERCISE 6(A) 
 
Solution: 
 
Question 1. 
Write the following sets in roster (Tabular) form : 
 
 
 
Question 2. 
Write the following sets in set-builder (Rule Method) form : 
 
Solution: 
 
Page 4


6. Sets 
EXERCISE 6(A) 
 
Solution: 
 
Question 1. 
Write the following sets in roster (Tabular) form : 
 
 
 
Question 2. 
Write the following sets in set-builder (Rule Method) form : 
 
Solution: 
 
Question 3. 
(i) Is {1, 2, 4, 16, 64} = {x : x is a factor of 32} ? Give reason. 
(ii) Is {x : x is a factor of 27} ? {3, 9, 27, 54} ? Give reason. 
(iii) Write the set of even factors of 124. 
(iv) Write the set of odd factors of 72. 
(v) Write the set of prime factors of 3234. 
(vi) Is {x : x
2
 – 7x + 12 = 0} = {3, 4} ? 
(vii) Is {x : x
2
 – 5x – 6 = 0} = {2, 3} ? 
Solution: 
(i) No, {1, 2, 4, 16, 64} ? {x : x is factor of 32} 
Because 64 is not a factor of 32 
(ii) Yes, {x : x is a factor of 27} + {3, 9, 27, 54} 
Because 54 is not a factor of 27 
(iii) 1 x 124 = 124 
2 x 62 = 124 
4 x 31 = 124 
Factors of 124 = 1, 2, 4, 31, 62, 124 
Set of even factors of 124 = {2, 4, 62, 124} 
(iv) 1 x 72 = 72 
2 x 36 = 72 
3 x 24 = 72 
4 x 18 = 72 
6 x 12 = 72 
8 x 9 = 72 
Factors of 72 = 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72 
Set of odd factors of 72 = {1, 3, 9} 
Page 5


6. Sets 
EXERCISE 6(A) 
 
Solution: 
 
Question 1. 
Write the following sets in roster (Tabular) form : 
 
 
 
Question 2. 
Write the following sets in set-builder (Rule Method) form : 
 
Solution: 
 
Question 3. 
(i) Is {1, 2, 4, 16, 64} = {x : x is a factor of 32} ? Give reason. 
(ii) Is {x : x is a factor of 27} ? {3, 9, 27, 54} ? Give reason. 
(iii) Write the set of even factors of 124. 
(iv) Write the set of odd factors of 72. 
(v) Write the set of prime factors of 3234. 
(vi) Is {x : x
2
 – 7x + 12 = 0} = {3, 4} ? 
(vii) Is {x : x
2
 – 5x – 6 = 0} = {2, 3} ? 
Solution: 
(i) No, {1, 2, 4, 16, 64} ? {x : x is factor of 32} 
Because 64 is not a factor of 32 
(ii) Yes, {x : x is a factor of 27} + {3, 9, 27, 54} 
Because 54 is not a factor of 27 
(iii) 1 x 124 = 124 
2 x 62 = 124 
4 x 31 = 124 
Factors of 124 = 1, 2, 4, 31, 62, 124 
Set of even factors of 124 = {2, 4, 62, 124} 
(iv) 1 x 72 = 72 
2 x 36 = 72 
3 x 24 = 72 
4 x 18 = 72 
6 x 12 = 72 
8 x 9 = 72 
Factors of 72 = 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72 
Set of odd factors of 72 = {1, 3, 9} 
 
 
Question 4. 
Write the following sets in Roster form : 
(i) The set of letters in the word ‘MEERUT’. 
(ii) The set of letters in the word ‘UNIVERSAL’. 
(iii) A = {x : x = y + 3, y ?N and y > 3} 
(iv) B = {p : p ? W and p
2
 < 20} 
(v) C = {x : x is composite number and 5 < x < 21} 
Solution: 
(i) Roster form of the set of letters in the word “MEERUT” = {m, e, r, u, t} 
(ii) Roster form of the set of letters in the word “UNIVERSAL” = {u, n, i, v, e, r, s, a, l} 
(iii) A = {x : x = y + 3, y ? N and y > 3} 
x = y + 3