So this part over here simplifies, and I can change the order to four x squared minus 100x plus 600. I just switched the order in which I'm writing them. So that's that, and so I can rewrite the volume of x as being equal to x times all of this business, which is, let me make sure I have enough space, let me do it a little higher, which is equal to four x to the third power minus 100x squared plus 600x. Now it'll be pretty straightforward to take the derivative. So let's say that v prime of x, v prime of x is going to be equal to, I just have to use the power rule multiple times, so four times three is 12x to the three minus one power, 12x squared, minus 200 times x to the first power, which is just x, plus 600. And so now we just have to figure out when this is equal to zero. So we have to figure out when 12x squared minus 200x plus 600 is equal to zero.