As we consider Cardano’s proof of our Great Theorem, one important concept to keep in mind is that much of our modern algebraic notation has not yet been developed. You can see an example in the text on page 146. An important following question is then: when was our modern algebraic notation developed, and by who? The second reading sheds some light on this question. An optional third reading gives a concise list of sources for the earliest uses of some common symbols.
Readings
First reading: Dunham, Chapter 6, pages 142 - 154
Second reading: A Brief History of Algebraic Notation
Third reading: Earliest Uses of Various Mathematical Symbols