A quadratic equation is a polynomial equation in which an independent variable appears with an exponent of two and no higher exponent. For example,
The numbers 5, 3 and 4 here are called coefficients: 5 is the coefficient of x2 and 3 is the coefficient of x.
By the fundamental theorem of algebra, a quadratic equation with real or complex coefficients has two complex roots (i.e., solutions), although the two roots may be equal. These roots can be computed using the quadratic formula.
See also: linear equation, cubic equation, quartic equation, quintic equation[?]
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