Question

Which of the following sets does not contain the element 9?

QUESTION 1 Which of the following sets does not contain the element 9? {x E Z+ x is the square of a positive integer} {{9}, {9}} {x € Z- xis a positive odd integer) {9.9. 19.9}}

Answer 1

The answer to the above problem is-

Which of the following sets does not contain the element 9?

OPTION 2- { {9}, {9} } - ANSWER

Option 1- Wrong Answer-

Reason- This set contains elements that are square of a positive integer.

So set will be S = { 1, 4, 9, 16...}

Since, element 9 is square of 3, so it belongs to this set.

So this option is wrong answer.

OPTION 2 - CORRECT ANSWER-

Reason - { {9}, {9} }

This set has two elements - {9} and {9} which is actually a set containing 9 and not element 9 itself. These are not equivalent to element 9.

So this option is a set that has set containing element 9 and this option is not a set containing element 9.

So this is the correct option.

Option 3- Wrong Answer

Reason - This set has elements that are positive odd integers. Since, element 9 is a positive integer that is odd, so it belongs to this set.

Set = { 1,3,5,7,9,11,13,...}

It contains element 9, so this option is wrong.

Option 4- Wrong Answer

Reason - { 9, 9, {9,9} }. It is very clear from the set itself that it has element 9. So this is also wrong answer.