And we want to take the derivative of this business. The derivative of f of x over g of x. The key realization is to just recognize that this is the same thing as the derivative of, instead of writing f of x over g of x, we could write this as f of x times g of x to the negative 1 power. g of x to the negative 1 power. And now we can use the product rule with a little bit of the chain rule. What is this going to be equal to? Well, we just use the product rule.