Let's say that I have the expression, let's say I'm interested in taking the derivative of x squared plus x minus two over x minus one. Which of these rules or techniques would you use? Well, you might immediately say, hey, look, this looks like a rational expression. I could say, look, I could say this is my f of x right over here. I could say this is my g of x right over here, and I could apply the quotient rule. This looks like a quotient of two expressions. And you could do that, and if you do all the mathematics correctly, you will get the correct answer.