What is a quadratic equation

In mathematics, a quadratic equation is a univariable polynomial equation of the second degree. A general quadratic equation can be written in the form

where x represents a variable or an unknown, and a, b, and c are constants with a not equal to 0. (If a = 0, the equation is a linear equation.)


The constants a, b, and c are called, respectively, the quadratic coefficient, the linear coefficient and the constant or free term. Quadratic equations can be solved by factoring (or "factorising" in British English), completing the square, using the quadratic formula, and graphing.


Solutions to problems equivalent to the equation were known to Babylonians as early as 2000 BC, as well as to early Indian, Chinese and Greek mathematicians. The first explicit solution appeared in India in 628 AD, and was developed into a general solution in Persia and India in the 9th and 10th centuries. It first appeared in its modern form in La Géométrie by René Descartes.