Or did she make a mistake, and where was that mistake? Alright, now let's just do it together. So she says that this is the derivative. I'm just going to reevaluate it here to the right of her work. So let's see, f prime of x is just going to be the chain rule. I'm going to take the derivative of the outside with respect to the inside. So this is going to be two-thirds times x squared minus one to the two-thirds minus one, so to the negative one-third power, times the derivative of the inside with respect to x.