Sec. 2.2 –
Complex Numbers
This section is covered mainly as review . You should already have learned about
complex numbers and how to use them in calculations and in simplifying expressions.
A
complex
number is so named because it is “complex”, that is, a difficult number, an
involved number, a complicated number.
A complex number is made up of two terms :
a
real
term and an
imaginary
term.
Remembering that a
1
i
 =
, a
pure
imaginary number is one of the form
bi
, where b
is a
real
coefficient.
Ex.
3
i
,
2
i

,
i
A complex number is defined as a number in the form
a + bi , where a and b are real
numbers. Ex. 2 3
i
+
,
7
i

,
1
i

,
2
7
i
+
Note that 3 is a
rational number
because 3 can be written in the form of a rational
number as
3
1
,
6
2
, etc.
Also, 3 is a complex number since 3 can be written in the form of a complex number
as
3 0
i
+
. And
the pure imaginary number 2
i
is a complex number since it can be
written in the form
0
2
i
+
. So the complex numbers include all of our numbers we
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 Fall '06
 Lebre
 Algebra, Complex Numbers, Complex number

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