So area is approximately, remember this is just a rough approximation, it's very clear actually. You might say this is pretty good using the trapezoids, but it is pretty clear that we are letting go of some of the area. We're letting go of that area, we're letting go of some of this right over here, you can barely see it, some of this right over here, you can barely see it. But we are, this is going to be, it looks like an underestimate, but it is a decent approximation. Let's see if we can simplify this expression. So it's approximately going to be equal to, I'm going to factor out a delta x over 2. And then what I'm left with, and I will switch to a neutral color, if I factor out a delta x over 2, then I have just an f of 1, and then I have 2 f of 2's, so plus 2 times f of 2, and I'm doing this because you might see a formula that looks something like this in your calculus book, and it's not some mysterious thing, they just really summed up the areas of the trapezoids.