LESSON 1
GENERAL MATHEMATICS REVIEW
Section I. PROPERTIES OF REAL NUMBERS
1-1.
DISCUSSION
Real numbers can be described as being the set of all x, such that x is the
coordinate of a point on a number line. The real numbers include the rational and
irrational numbers. Rational numbers include integers and quotients of integers.
Integers are whole numbers. Positive integers, such as 1, 2, 3, and so forth, are also
called natural numbers. An operation is a method of combining two elements of the set
of real numbers to form a third element (not exclusive). The properties of real numbers
depend upon two basic operations, addition and multiplication. This section is designed
to give you the concepts and skills necessary for the content and course work to follow.
1-2.
SOME FUNDAMENTAL PROPERTIES OF REAL NUMBERS
For any real numbers a, b, c, and d, the additive and multiplicative properties are
as follows:
a. Commutative Properties.
a+b=b+a
ab = ba
Examples:
3+5=5+3
2X4=4X2
b. Associative Properties.
(a + b) + c = a + (b + c)
(ab)c = a(bc)
Examples:
(2 + 1) + 4 = 2 + (1 + 4)
(4 X 3) X 2 = 4 X (3 X 2)
c. Identity Properties.
a+0=a
aX1=a
Examples:
3+0=3
7X1=7
MD0837
1-2