1. Section 4.6 Complex Numbers

6. it is a symbol for a specific number
Definition of pure imaginary numbers:
i is not a variable
it is a symbol for a specific number

7. Definition of pure imaginary numbers:
Any positive real number b,
where i is the imaginary unit and bi is called the pure imaginary number.

8. Simplify each expression.

9. Simplify each expression.
Remember
Remember

10. Definition of Complex Numbers
Any number in form a+bi, where a and b are real numbers and i is imaginary unit.

11. Definition of Equal Complex Numbers
Two complex numbers are equal if their real parts are equal and their imaginary parts are equal.
If a + bi = c + di,
then a = c and b = d

14. When adding or subtracting complex numbers, combine like terms.

15. Simplify.

16. Simplify.

18. Multiplying complex numbers.
To multiply complex numbers, you use the same procedure as multiplying polynomials.

19. Simplify. F O I L

20. Simplify. F O I L

23. To divide complex numbers, multiply the numerator and denominator by the complex conjugate of the complex number in the denominator of the fraction.
7 + 2i
3 – 5i
The complex conjugate of 3 – 5i is 3 + 5i.

24. 7 + 2i
3 – 5i
(3 + 5i)
(3 + 5i)
i + 6i + 10i2
9 + 15i – 15i – 25i2 i 34
i – 10
9 + 25