Republic of Mathematics blog

Posts Tagged ‘completing the square

What do we need to solve quadratic equations?

Posted by: Gary Ernest Davis on: June 11, 2011

Completing the square A former colleague wondered if the quadratic formula held when are complex numbers. He could, of course, have figured this out by the process of completing the square: If then exactly when (thanks to James Tanton for this trick). This happens exactly when or, equivalently when . This leads us to the […]