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300
Diophantus
Wrote piece containing a collection of many mathematical problems called "Arithmetica." In this piece, he deems a negative solution to an equation "absurd." -
620
Brahmagupta
Devised arithmetic operations for negative numbers in his work "Brahmasphuṭasiddhanta." Used the ideas of "fortunes" and "debts" to understand negative values. -
Period: 780 to 850
Al-Khwarizmi
Found solutions for quadratic equations using algebraic methods and geometrical diagrams. Became convinced by his geometric models that negative results were without real-world meaning. -
Period: to
John Wallis
Credited with incorporating negative numbers into the first number line. -
Francis Maseres
Claimed that negative numbers, "... darken the very whole doctrines of the equations and make dark of the things which are in their nature excessively obvious and simple." This thus showed his distaste for negative numbers because of their seeming disagreement with nature itself.