This video has been uploaded to algebra.com:
In this video lesson I explain how to solve quadratic inequalities using the quadratic formula. When solving quadratic inequalities, the most important step is to find the roots of the quadratic function in the inequality. If factoring doesn’t work, then you must use the quadratic formula. After you calculate the roots, this function is either less than zero between the roots and greater than zero everywhere else, or the opposite- the only thing this depends on is whether or not the graph of the quadratic opens up or opens down. This is easy to find out, and combined with the knowledge of the roots, gives us the solution to any quadratic inequality- but for more specifics and some examples, you should see the video!