The denominator was up here, x to the fourth plus 27 squared. x to the fourth plus 27 squared. That was our second derivative. Let's see if this changes signs around positive or negative 3. Actually, we should get the same answer, because regardless of whether we put positive or negative 3 here, you lose all your sign information, because you're taking it to the fourth power. You're taking it to the second power. Obviously, anything to the fourth power is always going to be positive.