And what I'm curious about is what is h prime of x? So I want to know h prime of x, which another way of writing it is the derivative of h with respect to x. These are just different notations. And to do this, I'm going to use the chain rule. And the chain rule comes into play anytime your function can be used as a composition of more than one function. And that might not seem obvious right now. But it will hopefully maybe by the end of this video or the next one.