Question

Width = (b - a)/n = (8 - 0)/4 = 2

2(f(0) + f(2) + f(4) + f(6))
2(-1 - 2.5 - 1.5 - 0.5)
2(-5.5)
-11

Is my answer C, -11? The question says four subintervals, so I used f(0), f(2), f(4), and f(6). I want to make sure that I am NOT supposed to be using f(8), because f(8) would give me a final answer of D. -13.5

Answer 1

I agree as well. The Riemann Sum diagram will look something like what you see in the attached images. I used GeoGebra to create the graph.

Answer 2

Yes, I'm getting C also!

Since it's asking for the left-endpoint Riemann Sum, you will only be using the top left point as the height for each of your four boxes, making -1, -2.5, -1.5, and -0.5 your heights. The bases are all the same length of 2. You don't include f(8) because you're not using right-endpoints, and that would also add another 5th box that isn't included in the 0 to 8 range.