So it looks like he's trying to apply the quotient rule. So applying the quotient rule, you would, in the numerator, you would take the derivative of the first expression times the second expression, and then minus the first expression times the derivative of the second expression, all of that over the, or I should say, the derivative of the numerator expression over the, or times the denominator expression, minus the numerator expression times the derivative of the denominator expression, all of that over the denominator expression squared. So this looks correct, actually. It's a correct application of the quotient rule. It looks like Tom is correctly simplifying. So the derivative of x to the 1 1⁄2 is 1 1⁄2 x to the negative 1 1⁄2, so that looks right. Derivative of x to the fourth is four x to the third, so that looks right.