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In general the term ‘quadratic’ refers to something involving a square, or the squaring of values, especially formulas or equations with squared terms.

### Algebra/Calculus/Precalculus

A quadratic polynomial is a function of the form

$p(x) = ax^2 + bx + c$

where $$a$$, $$b$$, and $$c$$ are real constants with $$a\neq 0$$. The roots of a quadratic polynomial may always be found via the quadratic formula:

$x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}$

The expression under the radical is called the determinant. If the determinant is positive, both solutions are real; if negative, both solutions are complex; and if zero, there is a single solution of multiplicity two.

The graph of a quadratic is a parabola, and if the roots are real they correspond to intercepts of the parabola on the $$x$$-axis.

Citation Info

• [MLA] “quadratic.” Platonic Realms Interactive Mathematics Encyclopedia. Platonic Realms, 27 Mar 2013. Web. 27 Mar 2013. <http://platonicrealms.com/>
• [APA] quadratic (27 Mar 2013). Retrieved 27 Mar 2013 from the Platonic Realms Interactive Mathematics Encyclopedia: http://platonicrealms.com/encyclopedia/quadratic/