Last updated at March 27, 2019 by Teachoo

Transcript

Ex 1.1,3 Write the following sets in roster form: (i) A = {x: x is an integer and –3 < x < 7}. Integers = ......-4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10…. The elements of this set are –2, –1, 0, 1, 2, 3, 4, 5, and 6 only. A = {–2, –1, 0, 1, 2, 3, 4, 5, 6} Note: Answer written in back of the book is incorrect. Please comment if written any mistake Ex 1.1,3 Write the following sets in roster form: (ii) B = {x: x is a natural number less than 6}. Natural numbers = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,…. So, the elements of this set are 1, 2, 3, 4, and 5 only. B = {1, 2, 3, 4, 5} Ex 1.1,3 Write the following sets in roster form: (iii) C = {x: x is a two-digit natural number such that the sum of its digits is 8} 8 = 0 + 8 , 8 = 1 + 7 , 8 = 2 + 6 , 8 = 3 + 5 , 8 = 4 + 4 , 8 = 5 + 3 , The elements of this set are 17, 26, 35, 44, 53, 62, 71, and 80 only. C = {17, 26, 35, 44, 53, 62, 71, 80} Ex 1.1,3 Write the following sets in roster form: (iv) D = {x: x is a prime number which is divisor of 60} Hence, the elements of the set are 2,3,5 Hence D = {2,3,5} Ex 1.1,3 Write the following sets in roster form: (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 be written in roster form as E = {T, R, I, G, O, N, M, E, Y} Ex 1.1,3 Write the following sets in roster form: (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 be written in roster form as F = {B, E, T, R}

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.