
A quadratic equation is an equation which can be written in the form ax^{2} + bx + c = 0 where a, b, and c are constants (as opposed to x, which is a variable). To solve an equation such as ax^{2} + bx + c = 0 by factoring, or by by completing the square, check out these links.
For quadratic equations which are difficult to factor, the Quadratic Formula will always
reveal solutions. Traditionally, these solutions are written:

Original Equation: 2x^{2} + 5x = 25 Rewritten equation: 2x^{2} + 5x  25 = 0 Identify values of "a", "b", and "c": a = 2, b = 5, c = 25 Substiture these values into the quadratic formula, to get: 

