1. College Algebra 1.5 Complex Numbers
2.4
Complex Numbers
Standard form of a complex number a + bi
Adding and Subtracting complex numbers
(3 – i) + (2 + 3i) =
2i + (-4 – 2i) =
3 - (-2 + 3i) + (-5 + i) =
5 + 2i -4
-2i

2. College Algebra 1.5 Complex Numbers
Multiplying Complex numbers
Note: i2 = -1
(i)(-3i) =
(2 – i)(4 + 3i) =
(3 + 2i)(3 – 2i) =
-3i2 = 3
8 + 6i – 4i – 3i2 =
11 + 2i
9 – 4i2 =
9 + 4 = 13 -6
Dividing Complex numbers

3. College Algebra 1.5 Complex Numbers
Note: -6 -3

4. College Algebra 1.5 Complex Numbers
Use the quadratic formula to solve
0 = 3x2 – 2x + 5

5. College Algebra 1.5 Complex Numbers
i1 = i
i2 = -1
i3 = -i
i4 =
(i2)2 =
(-1)2 = 1
i5 = i
What does i36 =
(i2)18 =
(-1)18 = 1
i53 = i