So let's say x equals a to x equals b, although it could have been from, this could have been a, that could have been b, but this is our interval. We're saying in general terms from a to b. And this will give our volume. This right over here is the volume of each washer, and then we're summing up all of the washers and taking the limit as we have an infinite number of them. So let's see if we apply this to the example in the last video, whether we get the exact same answer. Well, in the last video, y equals g of x was equal to x, and y is equal to f of x was equal to the square root of x. So let's evaluate that given what we just were able to derive.