Let's say that y is equal to seven to the x squared minus x power. What is the derivative of y, derivative of y, with respect to x? And like always, pause this video and see if you can figure it out. Well, based on how this has been color-coded ahead of time, you might immediately recognize that this is a composite function, or it could be viewed as a composite function. If you had a v of x, which if you had a function v of x, which is equal to seven to the x power, and you had another function u of x, u of x, which is equal to x squared minus x, then what we have right over here, y, y is equal to seven to something. So it's equal to v of, and it's not just v of x, it's v of u of x. Instead of an x here, you have the whole function u of x, x squared minus x.