Copy of Multiplying Complex Numbers

Use the sliders to control the positions of z1 and z2. The third complex number, z3, is the product of the first two.

Describe the process of multiplying two complex numbers.

The number 1 is the multiplicative identity, because any number n times 1 equals n. What would the multiplicative identity be in the complex numbers (in a+bi form)?

Set a and c equal to 2, set b equal to -3, and set d equal to 3. What is the product? What if you change b to 1 and d to -1? When two complex numbers have the same a value but opposite b values, they are called complex conjugates (or sometimes just "conjugates"). Try another set of complex conjugates. What do all of their products have in common? Why does that happen?

Let a=4 and b=0. Let c=0 and d=1. What is the product? Set a and b so that z1 is the same number as your product just was. Leave c and d the same. What is the new product? Do this two more times and record the product each time. Where did you end up?

You should now go to deltamath and complete the sections "Finding the Conjugate" and "Multiply Complex Numbers".