So the derivative of f, well, you take the derivative of the inside, so take the derivative of that right there, which is 4x to the third. And then multiply it times the derivative of the outside with respect to the inside. So the derivative of natural log of x is 1 over x. So the derivative of this whole thing with respect to this inside expression is going to be times 1 over x to the fourth plus 27. If you found that confusing, you might want to re-watch the chain rule videos. But that's the first derivative of our function. And I could rewrite this, this is equal to 4x to the third over x to the fourth plus 27, or I could write it as 4x to the third times x to the fourth plus 27 to the negative 1.