Quick look at complex numbers

i^2 = -1

z = a+bi

z(bar) = a - bi ~> this is called a conjugate of z

Solutions to quadratic equations with no real solutions will have solutions the form z and z(bar)

z + z(bar) = real number

z - z(bar) = imaginary number

z*z(bar) = real number

To do division of z/w(both in same form) multiply by conjugate of w for both top and bottom

In polar form

a = r cos theta

b = r sin theta

De Moivre's formula: https://en.wikipedia.org/wiki/De_Moivre's_formula