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. It's the derivative of the first function right over here. So it's going to be f prime of x times just the second function, which is just g of x to the negative 1 power, plus the first function, which is just f of x, times the derivative of the second function. And here we're going to have to use a little bit of the chain rule.