Solution: Roster form | Sets and Functions - JEE

1. 

The required numbers are 1, 2, 3, 4, 5. So, the given set in the roster form

is: P = {1, 2, 3, 4, 5}.

2. The Roster form for this set can be written as: 

Q = {L, O, Y, A}

While writing the set in roster form an element is not generally repeated, i.e., all the elements are taken as distinct. So, even though the word "LOYAL" has 5 characters, the set has only 4 members as we do not repeat the letter 'L' in the set.

3. Clearly, the set has infinite members as there are infinite odd numbers. We can represent this set in the Roster form using ellipsis (3 dots).

R = {1, 3, 5, 7, ...}

Note that all infinite sets cannot be described in the roster form. For example, the

set of real numbers cannot be described in this form, because the elements of this

set do not follow any particular pattern. Similarly, we can't describe the set of prime numbers in the roster form.

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