Algebra 1: 9.9 The Quadratic Formula & the Discriminant

The Quadratic Formula is probably the most useful and most popular way to solve a Quadratic (find the x-intercepts of a parabola). I even saw it inscribed on the tombstone of a kid who died when he was 18! This video explains how to do it and works through an example. Then it delves into the "Discriminant" and how it can be used to quickly answer some questions - basically how to use the discriminant to determine the number of real solutions without having to actually do the work of finding them.