Math 1310 Class Notes – Section 2.4, Page 1 of 6
Math 1310
Section 2.4
An Introduction to Complex Numbers
A complex number is a number that can be written in the form
bi
a
+
where
a
and
b
are
real numbers and
.
1
2

=
i
We call the number
a
the real part and we call the number
b
the imaginary part.
If
a
= 0, the complex number is called a pure imaginary number.
Any real number can be written as a complex number with
b
= 0.
•
First, you’ll need to be able to classify numbers as real, complex or both.
Example 1:
Identify each of these numbers as real, complex or both:
a.
i
2
4

b.
7
c.
36

d.
5
•
Identify the real part and the imaginary part
Example 2:
Write in the form
bi
a
+
and state the real part and the imaginary part.
a.
2
7
4
i
+
b.
9
5


c.
12
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View Full DocumentMath 1310 Class Notes – Section 2.4, Page 2 of 6
Next, you’ll need to be able to find various powers of
i
.
You’ll need to know these 4
powers:
i
1
1
*
1
*
*
1
*
1
2
2
4
2
3
2
=


=
=

=

=
=

=
i
i
i
i
i
i
i
i
i
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 Summer '08
 MARKS
 Real Numbers, Complex Numbers

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