The use of the letter x as a mathematical unknown is a relatively modern convention. Algebra has been around for a lot longer. Daryl Benson/Stockbyte via Getty Images You might be most familiar with x ...

I show how to solve math problems online during live instruction in class. This is my way of providing free tutoring for the students in my class and for students anywhere in the world. Every video is ...

Even though x is one of the least-used letters in the English alphabet, it appears throughout American culture – from Stan Lee’s X-Men superheroes to “The X-Files” TV series. The letter x often ...