Question

Q3:which of the following is false
1.all infinite set cannot be described in the
roster form
2.a set does not changes in if one are more
elements of the set are repeated
3.set of a rational number is subset of natural
number
4.commutative law follows in operations of
intersection of two sets​

Answer 1

Answer:

The set theory was developed by German Mathematician Georg Cantor

(1845-1918). He first encountered sets while working on ‘problems on

trigonometric series’. This concept is used in every branch of Mathematics i.e.,

Geometry, Algebra, etc.

In our daily life, while performing our regular work, we often come across a

variety of things that occur in groups.

e.g., Team of cricket players, group of tall boys, group of teachers, etc.

The words used above like team, group, etc., convey the idea of certain

collections.

Well-defined Collection of Objects

If any given collection of objects is in such a way that it is possible to tell

without any doubt whether a given object belongs to this collection or not,

then such a collection of objects is called a well-defined collection of objects.

e.g., ‘The rivers of India’ is a well-defined collection. Since, we can say that the

river Nile does not belong to this collection. On the other hand, the river

Ganga does belong to this collection.

Difference between Not Well-defined Collection and Well-defined Collection

Not Well-defined Collection Well-defined Collection

A group of intelligent students. A group of students scoring more than 95% marks of

your school.

A group of most talented writers

of India.

A group of odd natural numbers less t