1. 1.1 Writing Complex Numbers

2. Solve x2 - 4 = 0 and x2 + 4 = 0

3. Imaginary Numbers
In the real number system, there isn’t a number we can square to get -4. Imaginary numbers: Don’t think of them as “not real” Mathematicians chose this term for the pattern to describe the square root of a negative number after they thought all real numbers were identified

4. In Real-Life?

5. Vocabulary
Imaginary unit i : i = i2 =
Complex number:
Imaginary number:
Pure imaginary number:

6. Complex Numbers (a + bi)
Standard Form
Imaginary Numbers
(a + bi, b ≠ 0)
Real Numbers
(a + 0i)
Pure Imaginary Numbers
(0 + bi, b ≠ 0)

7. Write the complex number in standard form.

8. With a partner, do p. 3 #’s 1-10

9. Two Equal Complex Numbers
Two complex numbers a + bi and c + di are equal if and only if a = ___ and b = ___
Example:
Find real numbers x and y to make the equation true.
2x + 2yi = 6 + 4i
3x + 5yi = 9 – 15i

10. Homework
Pg. 4, 1 – 31 odds