In mathematics, a quadratic equation is a univariate 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 ≠ 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 term or free term. The term "quadratic" comes from quadratus, which is the Latin word for "square". Quadratic equations can be solved by factoring, completing the square, graphing, Newton's method, and using the quadratic formula (given below).

Negative P H - Calculations of PH - Weak Acids and Bases
... Electrical charges are omitted from subsequent equations for the sake of generality and its value is assumed to have been determined by experiment ... Two additional equations are needed ... In some texts one mass balance equation is replaced by an equation of charge balance ...
Generalization of Quadratic Equation - Characteristic 2
... In a field of characteristic 2, the quadratic formula, which relies on 2 being a unit, does not hold ... Consider the monic quadratic polynomial over a field of characteristic 2 ... there is only one root since In summary, See quadratic residue for more information about extracting square roots in finite fields ...
Elementary Algebra - Solving Algebraic Equations - Quadratic Equations
... A quadratic equation is one which includes a term with an exponent of 2, for example, and no term with higher exponent ... In general, a quadratic equation can be expressed in the form, where is not zero (if it were zero, then the equation would not be quadratic but linear) ... Because of this a quadratic equation must contain the term, which is known as the quadratic term ...
Loss Of Significance - A Better Algorithm
... A better algorithm for solving quadratic equations is based on two observations that one solution is always accurate when the other is not, and that given ... The above formulas (1) and (2) work perfectly for a quadratic equation whose coefficient 'b' is negative (b < 0) ... In our example, coefficient 'b' of quadratic equation is positive ...

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A nation fights well in proportion to the amount of men and materials it has. And the other equation is that the individual soldier in that army is a more effective soldier the poorer his standard of living has been in the past.
Norman Mailer (b. 1923)