# Lesson 04: Complex Numbers: Adding and Subtracting

Lesson on simplifying imaginary numbers. Imaginary numbers are numbers whose index are even numbers an radicands are negative. These numbers are usually undefined. By replacing sqrt -1 with I, we can solve for the value of the variables.

2:18 examples of complex numbers

3:10 (2+3i) + (5+8i)

4:21 (7+2i) - (-3 - 5i)

5:19 (3 + sqrt -25) + (8 - sqrt -1)

Lesson module on imaginary numbers: http://www.numberbender.com/lesson/mo...

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