You're probably tired of just talking in the abstract. So this is going to be equal to, this is going to be equal to, and I'm gonna write it out again, this is the derivative, instead of just writing v and u, I'm gonna write it, let me write it this way, this is going to be, I keep wanting to be using the wrong colors, this is going to be the derivative of, I'm gonna leave some space, times the derivative of something else with respect to something else. So we're gonna first take the derivative of v. Well v is cosine of x to the third power, cosine of x. We're gonna take the derivative of that with respect to u, which is just cosine of x, and we're gonna multiply that times the derivative of u, which is cosine of x, with respect to x, so this one we have good, we've seen this before. We know that the derivative with respect to x of cosine of x, cosine, let me use it in that same color, the derivative of cosine of x, well that's equal to negative sine of x. So this one right over here, that is negative sine of x. You might be more familiar with seeing the derivative operator this way, but in theory, you won't see this as often, but this helps my brain really grok what we're doing.