Q2 of 43 Page 6

Decide whether set A and B are equal sets. Give reason for your answer.

A = Even prime numbers


B = {x| 7x – 1 = 13}

We know that two sets A and B are said to be equal, if every element of set A is in set B and every element of set B is in set A. It is symbolically written as A = B.


A = Even Prime Numbers = {2}


B = {x| 7x – 1 = 13}


⇒ 7x – 1 = 13


⇒ 7x = 13 + 1 = 14


⇒ x = 14/7


∴ x = 2


∴ A = B


Ans. Set A and set B are equal sets.


More from this chapter

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5

Write the following sets using rule method. We know that in rule method, we do not write the list of elements but write the general element using variable followed by a vertical line or colon and write the property of the variable.

i. A = {1,4,9,16,25,36,49,64,81,100}


ii. B = {6,12,18,24,30,36,42,48}


iii. C = {S, M, I, L, E}


iv. D = {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}

 1

Decide which of the following are equal sets and which are not? Justify your answer.

A = {x|3x – 1 = 2}


B = {x | x is a natural number but x is neither prime nor composite}


C = {x |x ∈ N, x < 2}

 3

Which of the following are empty sets? Why?

i. A = {a |a is a natural number smaller than zero.}


ii. B = {x|x2 = 0}


iii. C = {x|5x – 2 = 0, x ∈ N}

 4

Write with reasons, which of the following sets are finite or infinite. We know that if a set is a null set or number of elements are limited and countable then it is called ‘Finite set’ and if number of elements in a set is unlimited and uncountable then the set is called ‘Infinite set’.

i. A = {x|x < 10, x is a natural number}


ii. B = {y |y< -1, is an integer}


iii. C = Set of students of class 9 from your school.


iv. Set of people from your village.


v. Set of apparatus in laboratory


vi. Set of whole numbers


vii. Set of rational number