Instead of an x here, you have the whole function u of x, x squared minus x. So it's v of u of x, and the chain rule tells us that the derivative of y with respect to x, and you'll see different notations here, sometimes you'll see it written as the derivative of v with respect to u, so v prime of u of x, times the derivative of u with respect to x, so that's one way you could do it, or you could say that this is equal to, this is equal to the derivative, the derivative of v with respect to x, derivative, or sorry, derivative of v with respect to u, dv du, times the derivative of u with respect to x, derivative of u with respect to x. And so either way, we can apply that right over here. So what's the derivative of v with respect to u? What is v prime of u of x? Well, we know, we know, let me actually write it right over here. If v of x is equal to seven to the x power, v prime of x would be equal to, and we proved this in other videos where we take derivatives, exponentials of bases other than e, this is going to be the natural log of seven, times seven to the x power.