This historic work consists of several treatises that developed the first consistent, coherent, and systematic conception of algebraic equations. Originally published in 1591, it pioneered the notion of using symbols of one kind (vowels) for unknowns and of another kind (consonants) for known quantities. Reprint of the Kent State University Press, Kent, Ohio, 1983 edition.
Here's a sample of other books in this Dover category
The Geometry of René Descartes by René Descartes The great work that founded analytical geometry. Includes the original French text, Descartes' own diagrams, and the definitive Smith-Latham translation. "The greatest single step ever made in the progress of the exact sciences." — John Stuart Mill.
The Early Mathematical Manuscripts of Leibniz by G. W. Leibniz, J. M. Child Leibniz's own accounts of his work, plus critical and historical notes and essays, include his "Historia et Origio Calculi Differentialis," manuscripts of the period 1673-77, and essays by C. I. Gerhardt.