So we need to figure out this thing right over here. So first, just like we did, we're just going to apply the chain rule again. We need to figure out the derivative of cosine of something, in this case, e to the x, with respect to that something. So this is going to be equal to derivative of cosine of something with respect to that something is equal to the negative sine of that something. Negative sine of e to the x. Once again, we can view this as the derivative of cosine of e to the x with respect to e to the x. And then we multiply that times the derivative of the something with respect to x.