There are three types of sums
- left sum
- right sum
- mid-point sum
Δx= b-a/n start-stop/# of rect.
In order to find the left sum you take the left side of each of the rectangles lengths and apply it to the equation and then add the sum together Δx(f(x₀)+f(x₁)+f(x₂)...)
To find the right sum you take the right side of the rectangles lengths and plug it into the equation and then add that sum up to get the right sum Δx(f(x₁)+f(x₂)+f(x₃)...)
In order to get he mid-point sum youre pretty much averaging the two points.