Solving Polynomial Equations
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Symmetry and the Cubic Formula
SYMMETRY AND THE CUBIC FORMULA DAVID CORWIN The purpose of this talk is to derive the cubic formula. But rather than finding the exact formula, I'm going to prove that there is a cubic formula. The way I'm going to do this uses symmetry in a very elegant way, and it foreshadows Galois theory. Note that this material comes almost entirely from the first chapter of http://homepages.warwick.ac.uk/~masda/MA3D5/Galois.pdf. 1. Deriving the Quadratic Formula Before discussing the cubic formula, I would like to consider the quadratic formula. While I'm expecting you know the quadratic formula already, I'd like to treat this case first in order to motivate what we will do with the cubic formula. Suppose we're solving f(x) = x2 + bx + c = 0: We know this factors as f(x) = (x − α)(x − β) where α; β are some complex numbers, and the problem is to find α; β in terms of b; c. To go the other way around, we can multiply out the expression above to get (x − α)(x − β) = x2 − (α + β)x + αβ; which means that b = −(α + β) and c = αβ. Notice that each of these expressions doesn't change when we interchange α and β. This should be the case, since after all, we labeled the two roots α and β arbitrarily. This means that any expression we get for α should equally be an expression for β. That is, one formula should produce two values. We say there is an ambiguity here; it's ambiguous whether the formula gives us α or β. -
Solving Cubic Polynomials
Solving Cubic Polynomials 1.1 The general solution to the quadratic equation There are four steps to finding the zeroes of a quadratic polynomial. 1. First divide by the leading term, making the polynomial monic. a 2. Then, given x2 + a x + a , substitute x = y − 1 to obtain an equation without the linear term. 1 0 2 (This is the \depressed" equation.) 3. Solve then for y as a square root. (Remember to use both signs of the square root.) a 4. Once this is done, recover x using the fact that x = y − 1 . 2 For example, let's solve 2x2 + 7x − 15 = 0: First, we divide both sides by 2 to create an equation with leading term equal to one: 7 15 x2 + x − = 0: 2 2 a 7 Then replace x by x = y − 1 = y − to obtain: 2 4 169 y2 = 16 Solve for y: 13 13 y = or − 4 4 Then, solving back for x, we have 3 x = or − 5: 2 This method is equivalent to \completing the square" and is the steps taken in developing the much- memorized quadratic formula. For example, if the original equation is our \high school quadratic" ax2 + bx + c = 0 then the first step creates the equation b c x2 + x + = 0: a a b We then write x = y − and obtain, after simplifying, 2a b2 − 4ac y2 − = 0 4a2 so that p b2 − 4ac y = ± 2a and so p b b2 − 4ac x = − ± : 2a 2a 1 The solutions to this quadratic depend heavily on the value of b2 − 4ac. -
On Popularization of Scientific Education in Italy Between 12Th and 16Th Century
PROBLEMS OF EDUCATION IN THE 21st CENTURY Volume 57, 2013 90 ON POPULARIZATION OF SCIENTIFIC EDUCATION IN ITALY BETWEEN 12TH AND 16TH CENTURY Raffaele Pisano University of Lille1, France E–mail: [email protected] Paolo Bussotti University of West Bohemia, Czech Republic E–mail: [email protected] Abstract Mathematics education is also a social phenomenon because it is influenced both by the needs of the labour market and by the basic knowledge of mathematics necessary for every person to be able to face some operations indispensable in the social and economic daily life. Therefore the way in which mathe- matics education is framed changes according to modifications of the social environment and know–how. For example, until the end of the 20th century, in the Italian faculties of engineering the teaching of math- ematical analysis was profound: there were two complex examinations in which the theory was as impor- tant as the ability in solving exercises. Now the situation is different. In some universities there is only a proof of mathematical analysis; in others there are two proves, but they are sixth–month and not annual proves. The theoretical requirements have been drastically reduced and the exercises themselves are often far easier than those proposed in the recent past. With some modifications, the situation is similar for the teaching of other modern mathematical disciplines: many operations needing of calculations and math- ematical reasoning are developed by the computers or other intelligent machines and hence an engineer needs less theoretical mathematics than in the past. The problem has historical roots. In this research an analysis of the phenomenon of “scientific education” (teaching geometry, arithmetic, mathematics only) with respect the methods used from the late Middle Ages by “maestri d’abaco” to the Renaissance hu- manists, and with respect to mathematics education nowadays is discussed. -
Cracking the Cubic: Cardano, Controversy, and Creasing Alissa S
Cracking the Cubic: Cardano, Controversy, and Creasing Alissa S. Crans Loyola Marymount University MAA MD-DC-VA Spring Meeting Stevenson University April 14, 2012 These images are from the Wikipedia articles on Niccolò Fontana Tartaglia and Gerolamo Cardano. Both images belong to the public domain. 1 Quadratic Equation A brief history... • 400 BC Babylonians • 300 BC Euclid 323 - 283 BC This image is from the website entry for Euclid from the MacTutor History of Mathematics. It belongs to the public domain. 3 Quadratic Equation • 600 AD Brahmagupta To the absolute number multiplied by four times the [coefficient of the] square, add the square of the [coefficient of the] middle term; the square root of the same, less the [coefficient of the] middle term, being divided by twice the [coefficient of the] square is the value. Brahmasphutasiddhanta Colebook translation, 1817, pg 346 598 - 668 BC This image is from the website entry for Brahmagupta from the The Story of Mathematics. It belongs to the public domain. 4 Quadratic Equation • 600 AD Brahmagupta To the absolute number multiplied by four times the [coefficient of the] square, add the square of the [coefficient of the] middle term; the square root of the same, less the [coefficient of the] middle term, being divided by twice the [coefficient of the] square is the value. Brahmasphutasiddhanta Colebook translation, 1817, pg 346 598 - 668 BC ax2 + bx = c This image is from the website entry for Brahmagupta from the The Story of Mathematics. It belongs to the public domain. 4 Quadratic Equation • 600 AD Brahmagupta To the absolute number multiplied by four times the [coefficient of the] square, add the square of the [coefficient of the] middle term; the square root of the same, less the [coefficient of the] middle term, being divided by twice the [coefficient of the] square is the value. -
A Historical Survey of Methods of Solving Cubic Equations Minna Burgess Connor
University of Richmond UR Scholarship Repository Master's Theses Student Research 7-1-1956 A historical survey of methods of solving cubic equations Minna Burgess Connor Follow this and additional works at: http://scholarship.richmond.edu/masters-theses Recommended Citation Connor, Minna Burgess, "A historical survey of methods of solving cubic equations" (1956). Master's Theses. Paper 114. This Thesis is brought to you for free and open access by the Student Research at UR Scholarship Repository. It has been accepted for inclusion in Master's Theses by an authorized administrator of UR Scholarship Repository. For more information, please contact [email protected]. A HISTORICAL SURVEY OF METHODS OF SOLVING CUBIC E<~UATIONS A Thesis Presented' to the Faculty or the Department of Mathematics University of Richmond In Partial Fulfillment ot the Requirements tor the Degree Master of Science by Minna Burgess Connor August 1956 LIBRARY UNIVERStTY OF RICHMOND VIRGlNIA 23173 - . TABLE Olf CONTENTS CHAPTER PAGE OUTLINE OF HISTORY INTRODUCTION' I. THE BABYLONIANS l) II. THE GREEKS 16 III. THE HINDUS 32 IV. THE CHINESE, lAPANESE AND 31 ARABS v. THE RENAISSANCE 47 VI. THE SEVEW.l'EEl'iTH AND S6 EIGHTEENTH CENTURIES VII. THE NINETEENTH AND 70 TWENTIETH C:BNTURIES VIII• CONCLUSION, BIBLIOGRAPHY 76 AND NOTES OUTLINE OF HISTORY OF SOLUTIONS I. The Babylonians (1800 B. c.) Solutions by use ot. :tables II. The Greeks·. cs·oo ·B.c,. - )00 A~D.) Hippocrates of Chios (~440) Hippias ot Elis (•420) (the quadratrix) Archytas (~400) _ .M~naeobmus J ""375) ,{,conic section~) Archimedes (-240) {conioisections) Nicomedea (-180) (the conchoid) Diophantus ot Alexander (75) (right-angled tr~angle) Pappus (300) · III. -
Analytical Formula for the Roots of the General Complex Cubic Polynomial Ibrahim Baydoun
Analytical formula for the roots of the general complex cubic polynomial Ibrahim Baydoun To cite this version: Ibrahim Baydoun. Analytical formula for the roots of the general complex cubic polynomial. 2018. hal-01237234v2 HAL Id: hal-01237234 https://hal.archives-ouvertes.fr/hal-01237234v2 Preprint submitted on 17 Jan 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Analytical formula for the roots of the general complex cubic polynomial Ibrahim Baydoun1 1ESPCI ParisTech, PSL Research University, CNRS, Univ Paris Diderot, Sorbonne Paris Cit´e, Institut Langevin, 1 rue Jussieu, F-75005, Paris, France January 17, 2018 Abstract We present a new method to calculate analytically the roots of the general complex polynomial of degree three. This method is based on the approach of appropriated changes of variable involving an arbitrary parameter. The advantage of this method is to calculate the roots of the cubic polynomial as uniform formula using the standard convention of the square and cubic roots. In contrast, the reference methods for this problem, as Cardan-Tartaglia and Lagrange, give the roots of the cubic polynomial as expressions with case distinctions which are incorrect using the standar convention. -
The Evolution of Equation-Solving: Linear, Quadratic, and Cubic
California State University, San Bernardino CSUSB ScholarWorks Theses Digitization Project John M. Pfau Library 2006 The evolution of equation-solving: Linear, quadratic, and cubic Annabelle Louise Porter Follow this and additional works at: https://scholarworks.lib.csusb.edu/etd-project Part of the Mathematics Commons Recommended Citation Porter, Annabelle Louise, "The evolution of equation-solving: Linear, quadratic, and cubic" (2006). Theses Digitization Project. 3069. https://scholarworks.lib.csusb.edu/etd-project/3069 This Thesis is brought to you for free and open access by the John M. Pfau Library at CSUSB ScholarWorks. It has been accepted for inclusion in Theses Digitization Project by an authorized administrator of CSUSB ScholarWorks. For more information, please contact [email protected]. THE EVOLUTION OF EQUATION-SOLVING LINEAR, QUADRATIC, AND CUBIC A Project Presented to the Faculty of California State University, San Bernardino In Partial Fulfillment of the Requirements for the Degre Master of Arts in Teaching: Mathematics by Annabelle Louise Porter June 2006 THE EVOLUTION OF EQUATION-SOLVING: LINEAR, QUADRATIC, AND CUBIC A Project Presented to the Faculty of California State University, San Bernardino by Annabelle Louise Porter June 2006 Approved by: Shawnee McMurran, Committee Chair Date Laura Wallace, Committee Member , (Committee Member Peter Williams, Chair Davida Fischman Department of Mathematics MAT Coordinator Department of Mathematics ABSTRACT Algebra and algebraic thinking have been cornerstones of problem solving in many different cultures over time. Since ancient times, algebra has been used and developed in cultures around the world, and has undergone quite a bit of transformation. This paper is intended as a professional developmental tool to help secondary algebra teachers understand the concepts underlying the algorithms we use, how these algorithms developed, and why they work. -
How Cubic Equations (And Not Quadratic) Led to Complex Numbers
How Cubic Equations (and Not Quadratic) Led to Complex Numbers J. B. Thoo Yuba College 2013 AMATYC Conference, Anaheim, California This presentation was produced usingLATEX with C. Campani’s BeamerLATEX class and saved as a PDF file: <http://bitbucket.org/rivanvx/beamer>. See Norm Matloff’s web page <http://heather.cs.ucdavis.edu/~matloff/beamer.html> for a quick tutorial. Disclaimer: Our slides here won’t show off what Beamer can do. Sorry. :-) Are you sitting in the right room? This talk is about the solution of the general cubic equation, and how the solution of the general cubic equation led mathematicians to study complex numbers seriously. This, in turn, encouraged mathematicians to forge ahead in algebra to arrive at the modern theory of groups and rings. Hence, the solution of the general cubic equation marks a watershed in the history of algebra. We shall spend a fair amount of time on Cardano’s solution of the general cubic equation as it appears in his seminal work, Ars magna (The Great Art). Outline of the talk Motivation: square roots of negative numbers The quadratic formula: long known The cubic formula: what is it? Brief history of the solution of the cubic equation Examples from Cardano’s Ars magna Bombelli’s famous example Brief history of complex numbers The fundamental theorem of algebra References Girolamo Cardano, The Rules of Algebra (Ars Magna), translated by T. Richard Witmer, Dover Publications, Inc. (1968). Roger Cooke, The History of Mathematics: A Brief Course, second edition, Wiley Interscience (2005). Victor J. Katz, A History of Mathematics: An Introduction, third edition, Addison-Wesley (2009). -
History of Mathematics Mathematical Topic Ix Cubic Equations and Quartic Equations
HISTORY OF MATHEMATICS MATHEMATICAL TOPIC IX CUBIC EQUATIONS AND QUARTIC EQUATIONS PAUL L. BAILEY 1. The Story Various solutions for solving quadratic equations ax2 + bx + c = 0 have been around since the time of the Babylonians. A few methods for attacking special forms of the cubic equation ax3 +bx2 +cx+d = 0 had been investigated prior to the discovery and development of a general solution to such equations, beginning in the fifteenth century and continuing into the sixteenth century, A.D. This story is filled with bizarre characters and plots twists, which is now outlined before describing the method of solution. The biographical material here was lifted wholesale from the MacTutor History of Mathematics website, and then editted. Other material has been derived from Dunham’s Journey through Genius. 1.1. Types of Cubics. Zero and negative numbers were not used in fifteenth cen- tury Europe. Thus, cubic equations were viewed to be in different types, depending on the degrees of the terms and there placement with respect to the equal sign. • x3 + mx = n “cube plus cosa equals number” • x3 + mx2 = n “cube plus squares equals number” • x3 = mx + n “cube equals cosa plus number” • x3 = mx2 + n “cube equals squares plus number” Mathematical discoveries at this time were kept secret, to be used in public “de- bates” and “contests”. For example, the method of depressing a cubic (eliminating the square term by a linear change of variable) was discovered independently by several people. The more difficult problem of solving the depressed cubic remained elusive. 1.2. Luca Pacioli. -
Solving the Cubic Equation
Solving the Cubic Equation Problems from the History of Mathematics Lecture 9 | February 21, 2018 Brown University A Brief History of Cubic Equations The study of cubic equations can be traced back to the ancient Egyptians and Greeks. This is easily seen in Greece and appears in their attempts to duplicate the cube and trisect arbitrary angles. As reported by Eratosthenes, Hippocrates of Chios (c. 430 BC) reduced duplicating the cube to a problem in mean proportionals: a : b = b : c = c : 2a: This idea would later inspire Menaechmus' work (c. 350 BC) in conics. The Greeks were aware of methods to solve certain cubic equations using intersecting conics,1 but did not consider general cubic equations because their framework was too influenced by geometry. 1One solution is due to Apollonius (c. 250-175 BC) and uses a hypoerbola. 1 A Brief History of Cubic Equations The Greek method of intersecting conics was completed by Islamic mathematicians. For example, Omar Khayyam (1048-1131) gave 1. examples of cubic equations with more than one solution 2. a conjecture that cubics could not be solved with ruler and compass 3. geometric solutions to all forms of cubics using intersecting conics While the techniques were geometric, the motivation was numeric: the goal in mind was to numerically approximate the roots of cubics.2 These ideas were taken back to Europe by Fibonacci. In one example, Fibonacci computed the positive solution to x3 + 2x2 + 10x = 20 to 8 decimal places (although he gives his solution in sexagesimal). 2Work done resembles Ruffini’s method. 2 Cubics in Renaissance Italy Cubics in Renaissance Italy The first real step towards the full algebraic solution of the cubic came from an Italian mathematician named Scipione del Ferro (1465-1526), who solved the depressed cubic3 x3 + px = q: Scipione del Ferro kept his method secret until right before his death. -
Cracking the Cubic: Cardano, Controversy, and Creasing Alissa S
Cracking the Cubic: Cardano, Controversy, and Creasing Alissa S. Crans Loyola Marymount University MAA MD-DC-VA Spring Meeting Stevenson University April 14, 2012 These images are from the Wikipedia articles on Niccolò Fontana Tartaglia and Gerolamo Cardano. Both images belong to the public domain. Wednesday, April 18, 2012 Quadratic Equation A brief history... • 400 BC Babylonians • 300 BC Euclid 323 - 283 BC This image is from the website entry for Euclid from the MacTutor History of Mathematics. It belongs to the public domain. Wednesday, April 18, 2012 Quadratic Equation • 600 AD Brahmagupta To the absolute number multiplied by four times the [coefficient of the] square, add the square of the [coefficient of the] middle term; the square root of the same, less the [coefficient of the] middle term, being divided by twice the [coefficient of the] square is the value. Brahmasphutasiddhanta Colebook translation, 1817, pg 346 598 - 668 BC √4ac + b2 b 2 x = − ax + bx = c 2a This image is from the website entry for Brahmagupta from the The Story of Mathematics. It belongs to the public domain. Wednesday, April 18, 2012 7 Quadratic Equation • 800 AD al-Khwarizmi • 12th cent bar Hiyya (Savasorda) Liber embadorum • 13th cent Yang Hui 780 - 850 This image is from the website entry for al-Khwarizmi from The Story of Mathematics. It belongs to the public domain. Wednesday, April 18, 2012 Luca Pacioli 1445 - 1509 Summa de arithmetica, geometrica, proportioni et proportionalita (1494) This image is from the Wikipedia article on Luca Pacioli. It belongs to the public domain. Wednesday, April 18, 2012 Cubic Equation Challenge: Solve the equation ax3 + bx2 + cx + d = 0 The quest for the solution to the cubic begins! Enter Scipione del Ferro.. -
A Short History of Complex Numbers
A Short History of Complex Numbers Orlando Merino University of Rhode Island January, 2006 Abstract This is a compilation of historical information from various sources, about the number i = √ 1. The information has been put together for students of Complex Analysis who − are curious about the origins of the subject, since most books on Complex Variables have no historical information (one exception is Visual Complex Analysis, by T. Needham). A fact that is surprising to many (at least to me!) is that complex numbers arose from the need to solve cubic equations, and not (as it is commonly believed) quadratic equations. These notes track the development of complex numbers in history, and give evidence that supports the above statement. 1. Al-Khwarizmi (780-850) in his Algebra has solution to quadratic equations of various types. Solutions agree with is learned today at school, restricted to positive solutions [9] Proofs are geometric based. Sources seem to be greek and hindu mathematics. According to G. J. Toomer, quoted by Van der Waerden, Under the caliph al-Ma’mun (reigned 813-833) al-Khwarizmi became a member of the “House of Wisdom” (Dar al-Hikma), a kind of academy of scientists set up at Baghdad, probably by Caliph Harun al-Rashid, but owing its preeminence to the interest of al-Ma’mun, a great patron of learning and scientific investigation. It was for al-Ma’mun that Al-Khwarizmi composed his astronomical treatise, and his Algebra also is dedicated to that ruler 2. The methods of algebra known to the arabs were introduced in Italy by the Latin transla- tion of the algebra of al-Khwarizmi by Gerard of Cremona (1114-1187), and by the work of Leonardo da Pisa (Fibonacci)(1170-1250).