Well, the derivative of three y squared with respect to x, that's going to be the derivative of three y squared with respect to y, which is just going to be six y, I'm just using the power rule there, times the derivative of y with respect to x. All I did just now is I took the derivative of that with respect to x, which is the derivative of that with respect to y times the derivative of y with respect to x, comes straight out of the chain rule, minus the derivative of this with respect to x, which is just going to be equal to one. All of that over, remember, we're in the middle of the quotient rule right over here. All of that over the denominator squared. All of that over three y squared minus x squared. Now lucky for us, they want us to evaluate this at a point as opposed to have to do a bunch of algebraic simplification here. So we can say when, let me do it over here.