Algebra 77 - The quadratic formula

Before the method of completing the square was developed, only very limited types of quadratic equations could be solved. This method eliminated those limitations, allowing the solutions of any quadratic equation to be found. As mathematics progressed, this methodology was eventually reduced to a formula. In this lecture, we will show how this "quadratic formula" can be derived from the process of completing the square, and show why the quadratic formula is so useful.