The Facts On File Algebra Handbook

EQUATIONs, in which he used a formula that was much

like the one used by Babylonians to solve QUADRATIC

EQUATIONs. GIROLAMO CARDANcalled del Ferro’s equation

“a gift from heaven.”

Fibonacci, Leonardo Pisano (Leonardo of Pisa, Leonardo

Bigollo, Leonardo Bonacci, Leonardo Bonaccio,

Leonardo Bonacij)(1170–1250) As a boy, this Italian

traveled extensively with his father and learned, through his

travels, about “the art of the Indians’ nine symbols,” which was

the Hindu-Arabic number system we use today. Fibonacci is

most famous for his first book Liber Abbaci(Book of the

Abacusor Book of Accounting) printed by hand and published

in 1202 (printing presses were not yet invented). Written in

Latin, this book explained addition, subtraction,

MULTIPLICATION, and division, using problems as examples, in

the Hindu-Arabic number system. It was responsible for

bringing this number system with the symbol ZERO(he called

it zephirum) to Europe as a replacement for the Roman

numeral system in use at the time, which has no symbol for

zero. It also introduced the famous FIBONACCI SEQUENCE, in

which a given number is the SUMof the two numbers

immediately before it. Fibonacci wrote several other books,

including Practica Geometria,geometry problems based on

EUCLID OF ALEXANDRIA’s work, Flos,dealing with the

approximation of ROOTs, and Liber Quadratorum,on number

theory, all of which have handwritten copies still in existence.

Flügge-Lotz, Irmgard (1903–74) German mathematician and

engineer who studied differential EQUATIONs and developed

the Lotz method for determining the lifting force on an aircraft

wing. In 1961, she became the first woman professor of

engineering at Stanford University.

Fourier, Jean-Baptiste-Joseph(1768–1830) French mathematician

who left his study of the priesthood for algebra, was nearly

beheaded for speaking out during the French Revolution, and

soon thereafter came under the service of Napoleon as

scientific adviser and founder of the Cairo Institute. Fourier is

known for his work on linear inequalities, and for Fourier’s

THEOREM, regarding the roots of an algebraic EQUATION.

While working under Napoleon, Fourier developed his theory

BIOGRAPHIES Fibonacci – Fourier

BIOGRAPHIES Fibonacci – Fourier

Jean-Baptiste-Joseph
Fourier (Courtesy of AIP
Emilio Segrè Visual Archives)