Lesson Series
We describe natural numbers, integers, rational numbers and real numbers.
We review inequalities and outline some basic methods for solving them.
We present here some basic rules of absolute values needed for many proofs.
We define the concept of a set and the notation of set definitions.
In this lesson we define the union and intersection of two sets. A union of two sets is another set whose elements are in either of the original two sets. An intersection of two sets is another set whose elements have to be in both of the original two sets.
We present the concept and notation of open and closed intervals on the real number line.
We define what it means for a set of numbers to be bounded.
The length of the intervals $[a,b]$, $[a,b)$, $(a,b]$, and $(a,b)$ are all $b-a$.
