Encounters with Cardano’s Method

Abstract

Many people, including ourselves, have been intrigued when first introduced to a story of inventing a formula for solving cubic equations. We invite the reader to recall a sixteenth-century story, in which characters possessing sonorous Italian names – del Ferro, Tartaglia, Cardano, and Bombelli – were on the stage. Different authors have depicted this story in relation to inventing complex numbers and legitimizing negative numbers (e.g., Guilbeaur 1930; Kenney 1989; Feldmann 1961). The story is an important milestone in the history of mathematics, and many teachers and mathematics educators like bringing it to a secondary school classroom or a course for mathematics teachers.