- NCERT Chapter

Question 3

# Write the following sets in roster form:

(i) A = {x: x is an integer and - 3 < x < 7}.

(ii) B = {x: x is a natural number less than 6}.

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

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

(v) E = The set of all letters in the word TRIGONOMETRY.

(vi) F = The set of all letters in the word BETTER.

(i) A = {x: x is an integer and - 3 < x < 7}.

(ii) B = {x: x is a natural number less than 6}.

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

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

(v) E = The set of all letters in the word TRIGONOMETRY.

(vi) F = The set of all letters in the word BETTER.

Answer

** (i)** A = {*x*: *x* is an integer and –3 < *x* < 7}

The elements of this set are –2, –1, 0, 1, 2, 3, 4, 5, and 6 only.

Therefore, the given set can be written in roster form as

A = {–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 be written in roster form as

B = {1, 2, 3, 4, 5}

**(iii)** C = {*x*: *x* is a two-digit natural 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, this set can be written in roster form as

C = {17, 26, 35, 44, 53, 62, 71, 80}

**(iv)** D = {*x*: *x* is a prime number which is a 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 be 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 be 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 be written in roster form as

F = {B, E, T, R}

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(i) 5__A

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(v) 2__A

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*n*terms in the geometric progression x^{3}, x^{5}, x^{7}... (if x ≠ ±1)">Find the sum to

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*n*terms of the series 3 × 1^{2}+ 5 × 2^{2}+ 7 × 3^{2}+ …

Kuldee
2019-09-26 13:18:11

Wonderful maths helper

shyamlal yadav
2019-05-27 22:49:18

good

Rajoo Prajapati
2019-05-19 06:23:39

Great explanation

T MAINA
2019-05-13 20:16:28

Wonderful maths helper

Mehboob
2018-10-21 10:33:08

What will be the answer for . Describe the set {xâ¬N:x is a perfect square,10

sandeepbhairagond
2018-09-17 21:41:46

Super interduce great

Angel mariya
2018-06-27 20:13:54

Thanks for the help

Lalit baro
2018-06-19 07:07:29

thanks

Akash Swarnakar
2018-05-22 20:56:12

I also can't understand the third one

sri ram kumar
2018-04-03 21:15:32

Thanks for help it is very nice site