Why is a function like y = x to the 2nd power called a quadratic when quad means 4?

Question

I just started teaching algebra again after being off for the summer.

Answer 1

Quadratic equations are called quadratic because quadratus is Latin for "square"; in the leading term the variable is squared.

Answer 2

Well the answers above sound fine but I had heard an other explanation which might also be true. People got interested in "quadratic" functions when they started to solve quadratic equations. Well of course those are equations of the form
ax^2+bx+c=d
and have 4 parameters, a, b, c, and d... Of course this was back when people still have not mastered algebra or good sense to subtract d from both sides to get a 3 parameter formula.

Answer 3

Any number to the second power will produce a square number. 4 squared is 16, which can be represented as a square made from 16 color tiles, four sides, each equal. All square numbers can be physically represented with tiles, and this is an excellent way for students to have a concrete means of understanding quadratics.

Answer 4

My college algebra teacher didn't know this either! Quadratic is the latin word for "squared". Quadratic does not mean 4, it means "to the power of 2". Search for a fuller explanation with Google. That's how I found the information for my teacher.

Answer 5

Because it has an x^2 (x SQUARED) term and a square has four sides.

The next logical question is why is x raised to the second power called "x squared." The reason for this is that if you have a square whose side length is x then the area of that square is given by the product of x with itself.

Answer 6

To the second power can also be called squared. A square has four sides.

Answer 7

And the next step up is called a cubic equation. Go figure.