8. Integers

    Negative representations: (discuss historic and present international)

    Integers: set of numbers: {..,-3,-2,-1,0,1,2,3,..}

        Positive Integers, Zero, Negative Integers (Set View via models or
        Measurement view via the number line); concept of negative being opposite of
        positive across pivot point at Zero)

8.1 Addition & Subtraction:

    Set Model: Cancel effect: 4 positives + 3 negatives [i.e. 3 (-) cancels 3 (+) leaving 1 (+)]

    Number Line Model: a positives + b negatives: move from
        Zero a units right and then b units left from new position

    Addition Properties: (if a, b, c are integers)
 
Closure: a + b is an integer Cumutative:

a + b = b + a

Associative:

(a + b) + c = a + (b + c)

Additive Inverse:

a + (-a) = 0

Identity :

a + 0 = a = 0 + a for all a

Theorem - Additive Cancellation for Integers:

If a + c = b + c, then a = b

Theorem - Inverse of opposite:

 - ( - a ) = a

8.2 Multiplication, Division, and Ordering Integers:

    If a and b are integers: 

           1. 
 

            2. 

            3. 

    Multiplication Properties: (if a, b, c are integers)
 
Closure: ab is an integer Cumutative:

a x b = b x a

Associative:

(ab)c = a(bc)

Identity:

a x 1 = a

Distribution: (Multipilcation over addition):

a( b + c ) = ab + ac

Multiplication Cancellation:

Ac = bc, then a = b 

Zero Divisors:

ab = 0, iff a = 0 or b = 0 or both = 0

Theorem - Multiplication by -1:

 a (-1) = - a

Theorem - Multiplication of (-):

 Case 1: (-a)b = -(ab)

 Case 2: (-a)(-b) = ab

 

    Scientific Notation: An exponential representation of numbers in the form:

            

            Where a is called the mantissa and n the characteristic of exponent

    Ordering Integers Properties: (if a, b, c are integers)
 
Transitive Properties: 

If a < b and b < c, then a < c

< addition:

If a < b, then a + c < b + c

< Multiplication by (+):

If a < b, then ac < bc

< Multiplication by (-):

If a < b, then a(-c) > a(-c)

Use number line to order integers