*Macmillan Science Library: Mathematics*. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.

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## Quadratic Formula and Equations

A quadratic equation is an equation of the second degree, meaning that for an equation in *x*, the greatest exponent on *x* is 2. Quadratics most commonly refer to vertically oriented parabolas—that is, parabolas that open upward or downward. The graph of a vertically oriented parabola has the shape of a rounded "*v*," and the bottom-most (or top-most) point is called the vertex.

The equation for a parabola is usually written in either standard or vertex form; however, the standard form is more commonly used to solve for the *x*-intercepts, or roots. The standard form is *y = ax*^{2}*+ bx + c* for any real numbers *a*, *b*, *c* where *a* ≠ 0. The vertex form is *y - k = a*(*x - b*)^{2} with vertex (*b*, *k*) and where *a* ≠ 0.

Because *x*-intercepts are the points at which the graph crosses...

This section contains 1,498 words(approx. 5 pages at 300 words per page) |