It is asking you to calculate the Riemann sum. It is not asking you to calculate the area. The Riemann sum calculates the area under the curve. Area above the curve could be considered "negative" area. In other words, -13.5 is correct.
I have this Riemann sum question: and I thought I knew how to do the left hand riemann sum but now I'm unsure. Basically I've used it before but when I try to with these points I'm just getting really confused because they're all under the x-axis. I had to kind of do it upside down. My answer was -13.5 but I wasn't sure if I should make it 13.5 because it's the area? Also, can you check to see if I did the math right for it? 13.5 negative or positive could be wrong :/ Thanks!
It is asking you to calculate the Riemann sum. It is not asking you to calculate the area. The Riemann sum calculates the area under the curve. Area above the curve could be considered "negative" area. In other words, -13.5 is correct.