A newer version of this program that includes exploring complex numbers using this program has been uploaded. Click the link above to get to the new improved program. Thanks.
This video demonstrates how to program the TI 83 and TI 84 series of graphing calculators to use the quadratic formula, (-b + or - sqrt b^2 - 4ac)/2a. The discriminant is explained briefly. The use of the formula is also demonstrated for two equations. One situation shows two real roots and another no real solutions.