Thanks, I got it.

But if you don't know the class width, you probably can't do it ahead of

time. Like divide by

.

But that only works for y=constant?

What I mean is

so the 1/x is like dividing by the class width.

But it doesn't work if it is another function because

and then divide by class width.

But this is different than the following where I divide by

first:

And

clearly is not the same as

.

Sorry I left out the dx's in the equations; I don't understand what they are yet. I know it is an incremental piece of x, but I don't know where it is

coming from. Does it appear when you decide to take the integral with

respect to x?