Yesterday in my Geometry classes, we came across our first quadratic equation of the year. I mentioned that I had no idea why quadratics (which have a variable to the second power) have that name, since "quad" normally means "4." And that someday, when I'm online and bored, I was going to look it up. I just received this email: Dear Mrs. Aliceacc, I was bored while on the Internet and decided to look this up. The Website I recieved the information on is located below though the spaces need to be removed: Web Site: http:// mathforum. org/library/drmath/view/52572.html Date: 05/22/99 at 20:40:32 From: Doctor Peterson Subject: Re: Why is an equation having only two roots, one of which is raised to 2, called a "quadratic equation"? People often wonder about the word "quadratic," because they know that "quad" usually means "four," yet quadratic equations involve the second power, not the fourth. But there's another dimension to the word. Although in Latin the prefix "quadri" means four, the word "quadrus" means a square (because it has four sides) and "quadratus" means "squared." We get several other words from this: "quadrille," meaning a square dance; "quadrature," meaning constructing a square of a certain area; and even "square" (through French). Quadratic equations originally came up in connection with geometric problems involving squares, and of course the second power is also called a "square," which accounts for the name. The third-degree equation is similarly called a "cubic," based on the shape of a third power. Then when higher-degree equations began to be studied, the names for them were formed differently, based on degree rather than shape (since the Romans had no words for higher-dimensional shapes), giving us the quartic, quintic, and so on. In fact, quartic came along later; originally a fourth degree equation was called "biquadratic," meaning "doubly squared," which mixes the two concepts and is doubly confusing. So here's a table of names for polynomials and their sources: degree name shape dimension ------ --------- ------ --------- 1 linear line (1) 2 quadratic square (2) 3 cubic cube (3) 4 quartic - 4 5 quintic - 5 I don't really care much about the answer. But I LOVE that one of my kids did care enough to find out!