Question 697812
This is known as the quadratic formula and it is used to solve equations in the form {{{ax^2+bx+c=0}}} for x. 


You can read more about it at the following links



<a href="http://www.purplemath.com/modules/quadform.htm">http://www.purplemath.com/modules/quadform.htm</a>


<a href="http://en.wikipedia.org/wiki/Quadratic_equation">http://en.wikipedia.org/wiki/Quadratic_equation</a>


<a href="http://www.sosmath.com/algebra/quadraticeq/quadraformula/quadraformula.html">http://www.sosmath.com/algebra/quadraticeq/quadraformula/quadraformula.html</a>