Q7 of 23 Page 30

Write the following sets in roster form.

(i) A = {x : is a natural number greater than 50 but smaller than 100}


(ii) B = {x : x is an integer, x2 = 4}


(iii) D = {x : x is a letter in the word “LOYAL”}

We know that in roster method, we write all the elements of a set in curly brackets. Each of the element is written only once and separated by commas. The order of the element is not important but it is necessary to write all the elements of the set.


(i) A = {x: x is a natural number greater than 50 but smaller than 100}


⇒ Natural numbers greater than 50 are 51, 52, 53… and smaller than 100 are … 97, 98, 99.


∴ A = {51, 52, 53 … 97, 98, 99}


(ii) B = {x: x is an integer, x2 = 4}


⇒ Given x2 = 4


⇒ x = √4


∴ x = ±2


∴ B = {+2, -2}


(iii) D = {x : x is a letter in the word “LOYAL”}


∴ D = {L, O, Y, A}


More from this chapter

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5

Write the following sets in roster form.

(i) B = {x : x is a natural number smaller than 6}


(ii) C = {x : x is a two-digit natural number such that the sum of its digits is 8}.


(iii) D = {x : x is a prime number which is a divisor of 60}.


(iv) E = {x : x is an alphabet in BETTER}.

 6

Write the following sets in the set-builder form.

(i) {3, 6, 9, 12}


(ii) {2, 4, 8, 16, 32}


(iii) {5, 25, 125, 625}


(iv) {1, 4, 9, 16, 25 … 100}

 8

Match the roster form with set builder form.

(i) {1, 2, 3, 6}


(ii) {2, 3}


(iii) {M, A, T, H, E, I, C, S}


(iv) {1, 3, 5, 7, 9}


(a) {x : x is prime number and a divisor of 6}


(b) {x : x is an odd natural number smaller than 10}


(c) {x : x is a natural number and divisor of 6}


(d) {x : x is a letter of the word MATHEMATICS}

 1

If A = {1, 2, 3, 4}; B = {1, 2, 3, 5, 6} then find and Are they equal?