So we're going to work through it, and there's a chance that you might see it in your calculus class. So let's start with either one of these expressions up here. So let's start with the expression, well let's start with the, let's do this one over here. So if we have g of h of x is equal to x, h of x is equal to x, so we put that h of x back there, which is by definition true if g and h's are inverses. Well now let's take the derivative of both sides of this. So let's take the derivative with respect to x of both sides, derivative with respect to x. And on the left hand side, well we just apply the chain rule.