Maybe this will help, someone will explain it better soon no doubt

When doing the LRAM summation you choose a width of x for your rectangles (like 1/2) and then you cut up the graph into sections. The find the area of each rectangle by multiplying base times height. With the Left RAM you choose the y value at the top left corner of each rectangle. So the sum is

width*height (height is the y value at the left top corner)

width is always whatever you chose at the beginning like 1/2 for example

1/2 * 0 + 1/2 * (1/2)^2 + 1/2 * (1)^2 + 1/2 * (3/2)^2

Hopefully that helps a little, I am not sure exactly what you meant