13 - Add and Multiply Imaginary Numbers - Part 1

View more at http://www.MathTutorDVD.com. In this lesson we will learn how to add expressions and multiply expressions that contain imaginary numbers. We add imaginary numbers as we usually do in algebra by adding like terms. We also multiply imaginary expressions in the same way, but if we ever get i squared (i^2) in the answer then we replace that with a -1.