Thus, the roots of a quadratic function are given by,[br][img width=229,height=74]http://www.biology.arizona.edu/biomath/tutorials/quadratic/images/rootseqn3.gif[/img][br]This formula is called the quadratic formula, and its derivation is included so that you can see where it comes from. We call the term [i]b[/i][sup]2[/sup] −4[i]ac[/i] the discriminant. The discriminant is important because it tells you how many roots a quadratic function has. [br][br][table][tr][td]1. [i]b[/i][sup]2[/sup] −4[i]ac [/i]< 0 There are no real roots.[br]2. [i]b[/i][sup]2[/sup] −4[i]ac[/i] = 0 There is one real root.[br]3. [i]b[/i][sup]2[/sup] −4[i]ac [/i]> 0 There are two real roots.[br][/td][/tr][/table]