The form like a + bi is a complex number, where i is the imaginary unit and a and b are real numbers. So complex number has real part of a and the imaginary part of b.
The online Complex Number Exponents Calculator provides Exponent operation.
r1 = x1 + y1i
r2 = x2 + y2i
xy = (x1 + y1i)x2 + y2i.