What Is A Set

Sets:

A set is a collection of objects (called elements).

E.g. A = {1,4,6}. We use curly brackets.

This means that 1,4 and 6 are elements of the set A.

The order doesn`t matter: E.g. {1,4,6} = {6,1,4}.

We don`t write repeats: E.g. {1,4,4,4,6} would be incorrect.

Important sets:

Natural numbers N = {1,2,3,4,5,...}

Integers Z = {...,-3,-2,-1,0,1,2,3,...}

Rational numbers Q i.e. Numbers that can be written as a/b where a and b are integers (e.g. 1/2, -3/4, 5 etc.)

Real numbers R ;i.e. All Rational AND Irrational numbers (e.g. pi, surds etc.) i.e. The whole number line!