Well, before, they told us, they gave us the curve of the equation, and they also told us what dy dx is. Let me just rewrite them again just so we have them there. So we know that y to the third minus xy is equal to two. This is the equation of our curve. And we know that dy dx is equal to y over three y squared minus x. So one thing that we could do is, well, let's just figure out what the derivative of x with respect to y is and set that to be equal to zero. So this is the derivative of y with respect to x.