Solve Abu Kamil's Algebra Puzzle from 9th/10th Century

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SUMMARY

The discussion revolves around solving a mathematical puzzle attributed to the 9th/10th century Islamic mathematician Abu Kamil. The problem involves dividing the number ten into three parts (a, b, c) such that the equations a + b + c = 10, aa + bb = cc, and ac = bb hold true. The solution process includes manipulating these equations to derive relationships between the variables, ultimately leading to expressions for a, b, and c in terms of x, where x = a/c. This historical puzzle illustrates the early development of algebraic concepts.

PREREQUISITES
  • Understanding of basic algebraic equations
  • Familiarity with quadratic equations and their solutions
  • Knowledge of mathematical notation and terminology
  • Awareness of historical mathematical figures, specifically Abu Kamil
NEXT STEPS
  • Explore the historical context of Islamic mathematics in the 9th and 10th centuries
  • Study the methods used in solving quadratic equations
  • Investigate the contributions of Abu Kamil to algebra
  • Learn about the evolution of algebraic notation and its significance
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Mathematicians, educators, students of history, and anyone interested in the development of algebraic concepts and historical mathematical puzzles.

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"One says that ten is divided into three parts, and if the small one is multiplied by itself and added to the middle one multiplied by itself, it equals the large one multiplied by itself, and when the small is multiplied by the large, it equals the middle multiplied by itself."

This is a problem of 9th/10th century Islamic mathematician Abu Kamil. I found it in a an issue of Science in a review of "Unknown Quantity", a book about the history of algebra. It kept me entertained while I was waiting for a professor, see if you can figure it out. On a side note, the author's response to the review of his book, along with a reproduction of the review itself, are here.
 
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a <= b <= c
a + b + c = 10
aa + bb = cc
ac = bb
aa + ac = cc
a/c + 1 = c/a
let x = a/c
x + 1 = 1/x
xx + x - 1 = 0
x = (-1 + sqrt(1 + 4))/2 = a/c
xcc = bb
b = sqrt(x)c
cx + sqrt(x)c + c = 10
c = 10/(x + sqrt(x) + 1)
a = cx
b = sqrt(x)c[/color]
 
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