Lecture notes for Section 1.1

1. Section 1.1 ­ Real Numbers and Number Operations A.notebook July 29, 2009
Section 1.1 ­ Real Numbers and Number Operations
Subsets of Whole Numbers: 0, 1, 2, 3 …
Real
Number
Integers: ­3, ­2, ­1, 0, 1, 2, 3…
Rational Numbers: numbers that can
be expressed as a ratio,
like ¾, ½, ­5/8
Irrational Numbers: numbers that
cannot be expressed as a ratio,
like π or √2
1

2. Section 1.1 ­ Real Numbers and Number Operations A.notebook July 29, 2009
Using Real Example: Graph the numbers
Numbers √2, 2.7, and ­4/3 on a
number line and order them
from least to greatest.
­5 ­4 ­3 ­2 ­1 0 1 2 3 4 5
Properties Let a, b, and c be real numbers
of Numbers
Commutative:
a + b = b + a addition
ab = ba multiplication
Associative:
(a + b) + c = a + (b + c) addition
(ab)c = a(bc) multiplication
Distributive:
a(b + c) = ab + ac
2

3. Section 1.1 ­ Real Numbers and Number Operations A.notebook July 29, 2009
Properties Let a, b, and c be real numbers
of Numbers
Identity:
a + 0 = a addition
a ∙ 1 = a multiplication
Inverse:
a + (­a) = 0 addition
a ∙ 1/a = 1; a ≠ 0 multiplication
Homework Section 1.1 Worksheet #2 ­ 28 even
3