The complex numbers C

Cardano used "complex numbers" in order to obtain solutions of cubic equations, but this was quite tentative.

The algebraic rules how to manipulate these "complex numbers" where formulated by

Rafael Bombelli                 
1526 (Bologna) - 1572 (Rome)                 

in his book L'Algebra, published 1572.

(He wrote about the presentation in Cardano's book Ars Magna - "Ma nel dire fu oscuro").

These "complex numbers" are of the form a +bi
  • here i denotes a "root" of -1
  • and a, b are real numbers