Origin of the word Quadratic
Date: 04/07/98 at 23:34:28 From: Paul Wilson Subject: Why call it "quad"ratic? it has Two terms! Dr. Math, I am in the middle of a unit on quadratic equations with my algebra I students. We discussed monomials, binominals, trinomials, and so on. The problem started with a discussion about the different types of equations: mono means one, bi means two, tri means three, but when we started "quad"ratic eqautions, the big question was asked: If the degree of the equation is two why isn't it a "biadic" equation? I thought quad means four, but your highest power is two and at most you have three terms. I don't get it. The question I have for you: Why is it called "quadratic"? I tried dictionaries, searches, archives, etc. It was my guess, that the word is derived from Latin, but I haven't found someone to verify this. Can you help? Thanks for any help you can lend in this endeavor. P. Wilson
Date: 04/08/98 at 09:53:43 From: Doctor Sonya Subject: Re: Why call it "quad"ratic? it has Two terms! Well, here's what I was able to find out. Jeff Miller's History of Mathematics pages say that the word "quadratic" was first used in English in 1668 by John Wilkins (1614-1672) in an essay towards a real character, and a philosophical language [London: Printed for Sa. Gellibrand, and for John Martyn, 1668]. He wrote: "Those Algebraical notions of Absolute, Lineary, Quadratic, Cubic" (OED2). They don't say why he chose that word, though. We use the word quadratic because "quadra" refers to a square, and the leading term in a quadratic equation is "squared." This is consistent with calling a degree three polynomial a "cubic" for the leading term represents a cube. The word for an equation with a leading term of x^4 is "quartic." See also "Quadratic Equations" in our archives: http://mathforum.org/library/drmath/view/58332.html -Doctor Sonya, The Math Forum Check out our web site! http://mathforum.org/dr.math/
Date: 04/08/98 at 15:21:15 From: Sleprock01 Subject: Re: Why call it "quad"ratic? it has Two terms! Thank you. I will relay the info to my kids. That was my guess, but I just didn't find "quadra" to mean square!
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